Unit 3 Blog Reflection

Unit 3 Blog Reflection

This unit brought an even clearer understanding for me that physics is EVERYWHERE. Over Thanksgiving Break, I was watching a show on Netflix called Revenge. In the beginning of an episode the narrator said “Every action has an equal and opposite reaction.” Immediately I thought of Newton’s Third Law. 

Newton’s Third Law states that every action has an equal and opposite reaction. Newton’s second law can be explained in the formula  (a=Fnet/m)

which explains that accleration is directly proportional to force and indirectly proportional to mass. Newton’s Third Law can use this same formula but you can write it in a different way: (F=ma).

         An example where Newton’s Third Law is put into play can be seen when a large truck and a small car have a head on collision. The small car experiences the greater force because even though the truck and car exert the same force, the truck has a greater mass therefore the car will have a greater acceleration. We know this because of Newton’s third law, which states that every action has an equal, and opposite reaction. This means the mass and acceleration must equal each other out so that they will have the same force. This can be described in the formulas below:

F=ma

Car F (10N) =ma

Truck F (10N)=ma

            Continuing with Newton’s Third Law, we practiced action reaction pairs. If Margaret Anne pushes Naeem, Naeem pushes Margaret Anne. The key part about these reaction pairs is that the verb is the same (equal force) and the reaction is opposite. Another example is if an apple falls out of a tree. If the action force on the apple is the force of gravity on the apple, the reaction to that force would be apple pulls on earth. Of course, there are much more complicated examples as well. Imagine a book at rest on a table. One of the forces on the book is the support force and another force is the force of gravity on the book. So the action reaction pairs would be; Earth pulls apple downward and apple pulls earth upward. Table (support force) pushes apple upward and apple pushes table downward. So then, we moved on to an example that might help us understand more everyday things. For example, if forces are always equal and opposite then how does a horse pull a buggy forward?

This image is an attempt to show the different forces going on to cause the horse to pull the buggy forward. The reason the horse pulls a buggy is because of a few things. We know the horse exerts the same force on the buggy that the buggy exerts on the horse because of Newton’s Third Law which states that every action has an equal and opposite reaction. But the reason the horse and the buggy move forward is because the horse pushes on the ground with a greater force than the buggy pushes on the ground. A key part of this drawing is that the pink arrows are larger than the grey arrows to show that the horse has a greater force than the buggy. So here are the action reaction pairs; the grey would be buggy pushes on earth forward and earth pushes on buggy backward. The orange would be, the horse pulls buggy forward and the buggy pulls the horse backward. Lastly, the pink would be the horse pushes on the earth forward and the earth pushes on the horse backward.

            Then we moved on to vectors, which seemed really terrifying at first but turned out to be a lot easier and a lot more fun than I was expecting. A key example we used was a box on a ramp. Why does it go down the ramp? We figured out the reasoning by drawing vectors for the image.

You begin this drawing by drawing your fweight, which is the light blue line. You then draw the navy blue line above it and make sure it’s the same length as the fweight. This will allow you to draw the guide, which is the black line parallel to the ramp. From there, you draw your support force (fsupport), which is the red line, which must be perpendicular when it intersects the guide. Then you must draw lines that are equal in size and parallel to the fsupport and fweight. This creates the guide to draw the vector or the fnet, which goes diagonally through and must be parallel to the ramp. The fnet shows the direction in which the box is going, which is downhill.

This is another example of vectors. This shows which side of the rope will be more likely to break (the ropes are the black lines connected to the ball or circle. I started figuring this example out the same as the previous example; I drew the fweight and then I drew a line equal its length right above it (these are the blue lines). The blue line that is drawn above the fweight helps to draw the parallel lines. These green lines were drawn to be parallel to each of the ropes starting at the tip of the blue line. The pink lines were drawn to determine the outcome of the problem. The rope on the left will be more likely to break because it has greater tension. We know this because the vertical pink line is greater than the one on the right.

            Then we moved on to the universal gravitational force formula. This formula is:  F=G(m1m2/d^2) I saw this equation and immediately became discouraged. I thought this unit was going to turn into a complicated math unit that I wouldn’t understand and wouldn’t be able to relate it to my everyday life. However, my outcome was much different than my expectations. One of the first questions we were asked in this unit was “Where do you weigh more, at the ocean or on the top of Mt. Everest? Why?” My immediate response was that my weight would not change because when you tell someone like your doctor your weight you don’t say “Well I weigh 237 lbs. at the ocean but 234 lbs. at the top of Mount Everest.” Anyways I was proved wrong because I learned that I weigh more at the ocean because my gravitational pull is a lower elevation therefore it will be stronger. The distance is key. At the top of Mt. Everest I weight much less because I am at a much higher elevation therefore my gravitational pull will not be as strong.  The longer the distance the less force there is. The shorter the distance the bigger the force.  Also, I was reminded that although my weight would decrease my mass would remain the same. An astronaut weighs less in space because he or she is farther away from the earth therefore their gravitational pull is not as strong, however their mass remains the same.

            To put this equation into use we practiced a lot of problems. One of these problems asked us to find the gravitational force between the earth and the sun.  Presuming that G=7X10^-11 Nm^2/C^2 , the distance between the earth and the sun is about 2X10^11 and the mass of the earth is 6X10^24kg and the sun’s mass is 2X10^30. All I had to do was plug these numbers into the formula and cancel out the exponents to solve for the answer which is 21X10^21N.

            Learning about the earth’s gravitational pull brought us to the concept of tides. The force between the earth and the moon is greater than the force between the sun and the earth because the moon is CLOSER. Therefore, the moon affects these tides. Tides are caused by the difference in force felt by the opposite sides of the earth. Whichever side is closer to the moon will feel the greater force. There are two high tides and two low tides each day (4 tides per day total). High to low tide has a time span of 6 hours and from high tide to high tide and low tide to low tide there is a time span of twelve hours. There is not a specific time each day at which these tides occur. It’s constantly changing because the moon is constantly orbiting the earth. It takes about 27 days for the moon to complete a full orbit. There is a tidal bulge that forms around the earth. There are two tides we learned about called neap tides and spring tides. During spring tides the moon is either a full moon or a new moon and the tides are at its highest highs and lowest lows. Hurricane Sandy was so destructive because it came at a full moon therefore it was a spring tide so the tides were at its most extreme. If Hurricane Sandy had come during a neap tide or a half moon, the damage would have been much less severe. This is because during neap tides, the high tides aren’t as high as usual and they aren’t as low as usual. Here are images of each to show the position of the earth, moon, and sun during each of these tides.

This is an image of spring tides. There are two moons in this picture two show that the moon can either be to the left or right of the earth during spring tides. Also notice the tidal bulge is directed towards wherever the moon is.  The high tides will be where you see the tidal bulge and the low tides will be above and below the earth.

This is an image of neap tides. Again there are TWO moons in this picture to show that the moon can either be directly above or below the earth during neap tides. Also notice the tidal bulge is directed towards wherever the moon is.  The high tides will be where you see the tidal bulge and the low tides will be to the left and right of the earth. (High tides and low tides occur on opposite sides of the earth.)

            An important note to keep in mind when thinking about tides is that lakes don’t experience tides. Lakes don’t experience tides like the ocean does because the mass of the lake is not nearly big enough to be affected by the pull of the moon.             Next, we moved on to momentum and impulse. Momentum can be defined as inertia in motion or the product of the mass of an object and its velocity. Momentum= mass x velocity or Momentum=mv. To simplify this formula further, we use P to represent momentum so the official formula used to find the momentum of an object is P=mv. Impulse is the change in force.  Impulse= quantity force x time interval. Impulse= Ft. We use J to represent impulse. So the official formula is J=Ft. Impulse changes momentum. Therefore impulse= the change in momentum. Ft= change (mv). You can increase momentum by increasing the mass or increasing its speed. In other words to increase (change) impulse you can either increase the force or change the time interval. This was seen when we did the egg toss in class. Naeem and Ethan won because they decrease the impact in which the egg landed. They changed its momentum by increasing its time (which decreased its force).

P=mv

P=mv

P=mv

We must also take into consideration the conservation of momentum. This by definition states that in the absence of a new external force, the momentum of an object or system of objects is unchanged. The formula for this is mv(before)=mv(after). Therefore the change in P will always equal Pfinal-Pinitial.

Change in P= Pfinal- Pintial

Change in P=mvfinal-mvinitial

Take airbags into consideration. Why do airbags keep us safe? Air bags keep us safe because they slow down the force by increasing the time. The change in momentum is always the same with the dash or the airbag. P=mv. Change in P= Pfinal-Pinitial. If change in P is the always the same so is the impulse whether you hit the dash or the airbag. J=Change in P. However, the airbag increases the time of the impulse so the force on you is less. Small force=less injury. J=F(change)t. No airbag J=F(change)t

With airbag J=f(Change)time.

            Impulses are greater when an object bounces off an object. Impulse required to bring an object to a stop and then “throw it back again” is a greater impulse than the impulse required to just bring an object to a stop. This also ties into the conservation of momentum. Newton’s second law states that net force must be applied for acceleration. If you want to change momentum you must exert impulse. Only an impulse external to a system can change the momentum of the system. Otherwise the change in momentum will be the same before and after. For example, car bumpers are made of plastic and no longer made of rubber, which was popular for awhile, because the rubber bounces therefore a greater force would be exerted upon the car because according to Newton’s Third Law every action must have an equal and opposite reaction whereas plastic doesn’t bounce therefore the force exerted will be smaller. The plastic crumples which increases time however the impulse is the same.

Ja=-Jb

Change in Pa= -Change in Pb

Change in Pa+Change in Pb=0

Conservation of momentum says that impulse causes the momentum forces to be equal and opposite. Impulse causes the change in momentum.

Change in P=J

J=F(change)t

Ptotal before= Ptotal after

Ma+Va+Mb+Vb(before)=(Ma+Mb) Vab (after)

Momentum is only conserved with a system. The total momentum before and after are always the same but individually the momentums can change. 

Tides

In this picture, it is high tide. The water levels are at its highest point before shifting to low tide. Shifts from high tide to low tide occurs every six hours, therefore there are four tides per day (two high tides and two low tides).  These tides never occur at the same exact time each day. This is because the moon affects these tides. Tides are caused by the difference in force felt by opposite sides of the earth. The force between the earth and the moon is greater than the force between the sun and the earth because the moon is much closer. The moon takes 27 days to completely orbit around the earth. As a result the time of day and level of tides is constantly changing. There are spring tides that occur about two times a month. Spring tides are when the moon is directly in line with the sun and the earth. Spring tides have the highest high tides and the lowest low tides. The moon is full during spring tides.  There are also neap tides, which occur when the moon is directly above or below the earth. Neap tides are tides that don’t have the highest high or the lowest low.  The moon is halved during neap tides.  

Tides Resource

https://www.youtube.com/watch?v=aN2RM5wa1ek

Unit 2 Blog Post

            This unit we went into a lot more complex concepts than the first unit. This unit we learned about four specific concepts; free fall, throwing objects straight into the air, projectile motion, throwing objects at an angle, and falling through the air.

            To start off the unit we began with Newton’s second law of motion. This states that force causes acceleration therefore force is directly proportional to acceleration and acceleration is inversely proportional to mass. The formula for this law is (a=fnet/m).

            In the beginning we learned various formulas, once of which I just listed above. Well let’s say you’re given the mass of the object but you’re not given the weight of the object. Here, you would use (weight=(mass)x(gravity)). An example of this sort of problem would be “An object is given a mass of 50 kg. What is the objects weight?”  You could solve this simply by using this formula (w=mg). You would plug in 50 for m and 10 for g because gravity will always equal 9.8m/s^2 or the rounded version that we use of 10m/s^2. After plugging these numbers in you would get 500N. Remember all weight must be in Newtons for physics.

            Next, we learned about the concept of free fall. Free fall is when an object falls due to the effect of gravity alone. There is no other force acting the object besides gravity. This also dismisses air resistance from the equation. Here we are introduced to a few equations (d=at^2 or d=gt^2 and v=at or v=gt). In a free fall equation we can say that acceleration is equal to gravity because during free fall, it goes at a constant rate of 10m/s^2 and because the only force acting the object is gravity, that means the only force acceleration the object is gravity. So, gravity would equal (10m/s^2) as well. Here is a good example of free fall; “You drop an object from the top of the building and it takes 3 seconds to hit the ground. How high is the building and how fast was the object moving when it hit the ground. These were easy to solve with the new formulas we had been given. For the how far equation you would use (d=1/2gt^2).  You would then evaluate this equation and end up with (d=1/2(10)(3)^2). The answer would be 45 m tall building. For the second part of the question for the how fast answer you would just use the (v=gt) equation. (v=10(3)). Therefore it would be 30m per second. Going into more detail about objects in free fall, because the only force acting on an object in free fall all objects will hit the ground at the same time no matter what their weight is, as long as you are neglecting air resistance. Therefore when a penny and a feather are placed inside a vacuum tube, both will hit the ground at the same time because they are released from the same distance at the same time and there is no air resistance in this equation therefore the only force acting upon these objects is the force of gravity. To test free fall and better understand it, we did a lab where we estimated to calculate the actual height of 3^rd Anderson.

            After free fall we moved on to throwing things straight up into the air. Most of the properties of these go back to similar ones of that of free fall. We learned that the initial velocity of an object thrown into the air decreases by 10m/s^2 until it reaches the top of its path where it is still accelerating at 10m/s^2 but its velocity is 0m/s. This is known as its “hang time”. Some objects have more hang time than others based on their vertical distance. The vertical distance controls the amount of time an object will spend in the air.  As the ball continues back down towards the earth, again, it has an acceleration of 10m/s^2 and an increasing velocity before it hits the ground. An example of this would if an object were thrown straight into the air with an initial velocity of 40m/s (neglecting air resistance) how long will the ball spend in the air? What is the vertical distance of the ball? You would use the formulas (d=1/2gt^2 and v=gt) to find that the ball was in the air for 4seconds and it traveled about 80m to reach the top of its path.

            After mastering the concept of throwing objects directly into the air, we moved on to projectile motion. This is where the new concept of a horizontal and a vertical path. When an object, let’s say a package, is dropped from a plane moving through the sky, the path of this object may appear to be moving straight down if you were looking at from the plane, however, the real path of this package is more of a parabola, or diagonal line. Therefore, we have to take into consideration the vertical path and its horizontal path. The vertical velocity of the ball will continuously increase as it moves downward and it will have a constant acceleration. The vertical distance controls the time in which the ball will spend in the air. Again, we use the formulas we’ve used in the past to figure out all of these factors (d=1/2gt^2 and v=gt). Now however to figure out the horizontal velocity, which will remain constant and how far the ball moved in the horizontal direction, we use the formula (v=d/t). Time is constant for both the horizontal and vertical directions. Even if someone jumps father out, than the distance a person jumps upward, they person jumping farther out will land first because they don’t have as great of a vertical height. Therefore, when a bullet and its shell hit the ground at the exact same time even though the bullet travels father down field its because they both travel the same vertical distance, so when the two leave the gun the only force acting on these objects is the force of gravity. So the bullet may have a higher acceleration and the shell may have a higher velocity but the force of gravity pulls downward at the same exact time. This also answers the question “If a monkey lets go after a dart is fired at him, ill he avoid being hit? The answer is no, he will still be hit because the dart and the monkey started at the same height therefore; gravity will both pull them towards the ground at the exact same rate.

            The next part of this unit we learned was throwing things up at an angle. The vertical velocity controls the time an object is in the air. Because the gravity causes the velocity to decrease at 10m/s every second in the middle of an objects path being thrown into the air will always have a velocity of 0m/s. Now that we are throwing objects at an angle, we need to figure out the actual diagonal path it’s taking. We can do this by using the formula (a^2 + b^2 = c^2) or memorizing the most important triangles; 3,4,5, 30, 40, 50 or 1,1, 1.41,etc.

            The last section we worked on was falling through the air. Air resistance becomes stronger as you go faster. The force of air resistance increases causing the speed of an object to increase. Acceleration is decreased because net force is decreased. Velocity increases. To find the acceleration when an object is falling through the air you use the formula a=fnet/m. The only way for fair to decrease is for the skydiver to slow down because when the skydiver opens the parachute it causes everything to be off balance. Air resistance is much greater than its velocity. Therefore the object has to increase its velocity to decrease the air resistance an math its air resistance reaching terminal velocity. 

Falling through the Air Sources

http://www.youtube.com/watch?v=1AS-dCdYZbo -- fast forward to 3:30

this source explains the parachute scene
http://www.youtube.com/watch?v=ur40O6nQHsw

Throwing Objects into the Air

This is a picture of Jenny throwing her stuffed animal into the air in her room. The vertical velocity controls the time in which this stuffed animal will spend in the air. As the object is being thrown upward its velocity decreases at a constant 10m/s  and as it falls downward its velocity increases at a constant 10m/s. However the vertical acceleration will always remain constant and the horizontal acceleration will increase and the horizontal velocity will remain constant. In this picture, the dog has just reached its stopping point before it falls to the ground. Lets say, this dog was thrown up with a velocity of 20m/s, every second its vertical velocity will decrease by 10m/s. So after two seconds, it will be 0m/s at this point in the air. And as it falls to the ground it will increase by 10m/s. Why is this? Because the force of gravity causes the velocity to decreases an object thrown up into the air 10m/s so in the middle of its path it will always have a velocity of 0m/s. The formulas you would use to determine these The formulas you would use to determine the vertical path of this stuffed animal would be v=gt and d=1/2gt(squared) and the formulas you would use to determine its horizontal  path would be v=d/t. The vertical distance measured is associated with how high where as the horizontal difference is associated with the how far factor.

Free Fall Video

The video is a little weird...but it explains free fall pretty well.
http://www.youtube.com/watch?v=rom3psXk7Q8

Here are two different sources explaining Newton's second law of motion:

http://teachertech.rice.edu/Participants/louviere/Newton/law2.html

or I found this source too which is more of a video;

http://www.youtube.com/watch?v=iwP4heWDhvw

            In this unit I learned about a ton of physics. Primarily, I learned about inertia, acceleration, and velocity. But I learned much more than just general definitions and examples. I learned about every concept into great depth, which has brought me to a better understanding as to how these concepts relate to everyday life.

            I learned why it feels different to be in a car that is moving with cruise control on versus when it is speeding up, slowing down, or rounding a curve. If you’re in a car moving with cruise control, it feels like you’re not moving whereas if you are in a car that is speeding up, slowing down, or rounding a curve, you can feel the force being exerted upon the car.

            I learned that if we were in a frictionless environment, then we would never stop until some sort of force is acted upon us. We would not naturally slow down. For example, our class performed a lab involving a hovercraft. A hovercraft does not touch the ground therefore it does not face friction. If when someone is pushed on a hovercraft, friction is not a force that causes it to stop. The force that we used to stop our hovercraft when someone was on it was another person stopping him or her. If the hovercraft had not been stopped by one of us, it would have continued to move, because according to Newton’s first law of motion, “Every object continues in a state of rest or uniform speed in a straight line unless acted on by a nonzero net force.” In other words, an object will stay at rest until a force is acted upon it and an object will stay in motion unless a force is acted upon it. In the beginning, the hovercraft was at rest on the ground of the gym floor with a person on it who was also at rest and both stayed at rest until the force of the leaf blower caused the hovercraft to hover above the ground. It stayed at rest above the ground until someone pushed the hovercraft and once the hovercraft was moving, it would have continued to do so until someone forced it to stop.  

            In Newton’s first law of motion, he mentions net force. Net force is when more than a single force acts on an object. A force is simply a push or a pull. Force is measured in newtons. There are multiple types of force such as support force, gravitational, electrical, magnetic, muscular effort, etc. If there are multiple forces like these acting on an object it is called net force. Often examples of net force were used with the pushing and pulling of a box. If two people were pushing a box with equal force, (both pushing with 50 N), and another person was pushing the box in the opposite direction with 50 N. The net force would be 50N. If the net force on a car stopping were backward, you would lurch forward according to Newton’s first law of motion. Your body and the car were in forward motion, therefore when the car stops or goes backward, your body will want to continue in a forward motion.

            Another example that we have seen in this unit, explain the idea of inertia and its relationship with different forces involved throwing an object into the air. If an object is thrown up into the air, it will move continue to move upward until a force is acted upon it, according to Newton’s first law of motion. Here, there are multiple forces, such a gravitational and the weight of the object itself. Because there are multiple forces causing this object to come down, this object has a net force. Another factor that can fall under the category of force when involving inertia is mass. If a person has a larger mass the force will need to be stronger to move or stop whereas a person with less mass will require a smaller force to move or stop it.

            The next two concepts we moved onto after inertia were velocity and acceleration. Velocity is the speed of an object and its direction of motion. However, velocity is not the same idea as speed. Speed describes how fast something moves whereas velocity describes how was fast and in what direction. Velocity is “directed speed”. For example if a car were to travel at 60 kilometers per hour, we only know its speed; we do not know its velocity. However, if we say a car is traveling 60 kilometers per hour to the north we can specify its velocity. Velocity is changing if either the speed or the direction is changing, and it is changing if both its speed and direction are changing. For example, if a car on a curved track has a constant speed, its velocity will not constant. Its velocity is continuously changing because the car continues to change direction around the track. This explains the idea of changing velocity. Constant velocity is means both constant speed and direction. (Constant speed in other words is steady speed; it does not speed up or slow down.) Constant direction can only be a straight line. The path of the object cannot curve. Constant Velocity is motion in a straight line with a constant speed.

The formulas involving only constant velocity;

(You would usually use the term km/h)

Velocity=Distance/Time

Distance=Velocity x Time

Time= Distance/Velocity

            Acceleration is both the change in velocity and the time it took to change. The key word to remember when defining acceleration is the word, change.  Acceleration is a rate of a rate. Acceleration applies to both the increases and decreases in velocity. For example, let’s say there were four images of inclined planes. The greater the slope of the incline, the greater the acceleration of the ball.

The formulas involving only constant acceleration:

Acceleration=Change in Velocity/Time Interval

Acceleration= Vfinal-Vinitial/Time Interval

            If something has constant velocity it cannot have constant acceleration because constant acceleration means its getting faster where as constant velocity means it’s staying the same. Constant acceleration means an object such as the car is covering more ground per time interval where as constant velocity means the car is going at the exact same speed. So if the car in the video is going 60 miles per hour its acceleration is increasing where as its velocity is constant.

Formulas for Constant Acceleration:

Distance=1/2 Acceleration x Time x Time (how far equation)

Velocity= Acceleration x Time (how fast) ß usually used whne talking about the different inclines tested by Galileo.

Formulas for Constant Velocity:

Velocity= Distance/ Time (how fast)

Distance= Velocity/ Time (how far)

            Of course all of this information was a lot to learn and many of the concepts were very challenging to understand, but I think the both acceleration and velocity were the most difficult for me. Both of those were main points of this unit so being confused about acceleration and velocity might seem too broad, but it really took a lot for me to get the difference between these two correct. I often got the Change in Velocity over Time confused with the Distance over Time and got them mixed up between equations. Also, putting the definitions and idea into real life scenarios would throw me off a lot because I always knew the reasoning for what was happening or how much time it took for this or that but when putting that into words I really struggled. Another obstacle that really challenged me in this unit is just class discussion in general. I knew the answer in the back of my head for many questions asked in class, however, once I was supposed to say it out loud, I couldn’t. I soon began to just stop raising my hand in class because I knew my mind would go blank.

            I overcame my struggle to understand two of the three units main ideas by just reviewing notes and formulas a lot as well as writing the formulas down and plugging numbers into them. Also, I think by slowing the problem down a little bit and taking more time than I was before.

            This unit I definitely had my ups and downs with problem-solving skills and effort. I have a strong effort mind set but this unit when it came to consistently being on top of all my homework, all my blog posts, etc; I struggled significantly.  Most of the time I would think I completed all my homework, but then there would always be something else I didn’t do. When it came to blog posts, I would usually write them in study hall and then just forget to post them until after the assignment would do. Another factor that contributed to the downs in my efforts would definitely be confidence in physics. A lot of the time, I knew the answer but I thought I definitely had the wrong answer. Either way I should raise my hand, because either way I will gain better understanding by participating.

            My goals for next unit are definitely to improve everything I struggled with. To improve my lagging effort, next unit I will try to complete almost all of my homework, post all of my blogs on time, and raise my hand more in class. For the homework situation, I’m going to make a designated time to do my physics homework and at that time I will look at both the assignment sheet and my agenda book. To improve posting my blog posts on time, I will always finish the blog posts at night and as soon as I’ve finished the blog post I will post it to the group no matter what. Again, to improve my confidence in physics, I will just raise my hand for any question I think I have at least a plausible answer.

Here is the link to my podcast on Velocity; 

http://www.youtube.com/watch?v=RcJJaebEE20&feature=plcp

Here there is a group of people jumping into the air at different times. If they did not use their own force to jump, each of them would all stay at rest according to Newton’s first law called inertia, which states that an object at rest will stay at rest unless a force is acted upon it and an object in motion will stay in motion unless a force is acted upon it. Therefore, everyone who jumped would keep going upward but there are multiple forces, like the force of gravity, that pull them back down. Also, the amount of mass each person also is a also a force that stops them from continuously going upward. If a person has more mass, they will come down more quickly where as a person with less mass will take longer to come down. 

http://www.youtube.com/watch?v=VEz2Xm6zrW0&feature=fvst

This video shows both acceleration and velocity.
Velocity is the description of how fast something is moving and what direction they are moving in. The formula for velocity is; velocity equals distance over time. It describes the change in speed and direction. If a car, such as the car in this video, continues on a straight road, and is going at a speed of 80mph. It will continue at a constant velocity unless the velocity is increased or decreased. Changes in velocity occur when a car goes around a turn or hits the breaks.
Acceleration is how quickly velocity changes. The term acceleration applies to both the increases and decreases in velocity. Acceleration equals the change of velocity over the time interval (or the time it took to change). On this circular track, although the cars may not be increasing or decreasing their speed their acceleration is still changing due to the circular shape of the track. This causes a change in pace in which the car is going.
If something has constant velocity it cannot have constant acceleration because constant acceleration means its getting faster where as constant velocity means its staying the same. Constant acceleration means an object such as the car is covering more ground per time interval where as constant velocity means the car is going at the exact same speed. So if the car in the video is going 60 miles per hour its acceleration is increasing where as its velocity is constant.

Trip Blog Post

Trip Blog Post

            My initial answer for the trip problem was Aà 60km/h. I thought this was definitely the correct answer. I basically just averaged all the numbers together. Honestly, I didn’t use much of a process to think of the answer, I just sort of added and divided a couple numbers together and assumed that the number I got was the right answer.

            In class, however, after talking to my classmates, it was very clear that my answer was incorrect. It was brought to my attention that I left out the concept of time completely. One of the formulas I kept in mind to figure out the answer was;

Velocity= Distance/Time. The goal was for the motorist to go an average of 40 kilometers per hour. However, they had already gone for an hour and had averaged only 30 kilometers, therefore, the goal for reaching 40 kilometers per hour would have to be completed in a faster amount of time than the speed of light which would be virtually impossible.

            The correct answer was Dàfaster than the speed of light. I solved this by breaking each distance the motorist traveled into time frames. In the beginning, the motorist went 20 km with an average speed of 40km/h. The next distance he travels is only 10km averaging only 20km/h. The goal was for the motorist to go 40km/h in the last 10km. So, I took all of these factors into considering and used the formula that velocity=distance/time. I didn’t really use plug anything into that formula, however, writing it down reminded me to take time into consideration. So, that’s what I did. I realized that it had already taken the car an hour, therefore, the time that had been lost had to be made up into the idea that the car would move faster than the speed of light in order to maintain an average of 40km/h.

            At the beginning, looking at this problem, I was overwhelmed and the first few times reading over it I just couldn’t comprehend the idea. However, I learned that if you write all the equations relevant and you write all the numbers and problems out beneath the question it helps you to organize your thoughts as well as gain you points. 

Riding a hovercraft was far from what I was expecting. It definitely cannot compare to driving a car. It’s very different riding a hovercraft not only because you’re levitated in the air but also because the hovercraft just keeps going, the hovercraft doesn’t slow down, it continues until a force stops it. This is so different from a car or a sled or skateboard, or anything that runs on the ground because eventually those objects stop due to the friction of the ground but the hovercraft has no friction so it’s definitely a very strange experience to continue at a constant velocity until you force it to stop.

After completing and discussing this project, I have a much better understanding about inertia, net force, and equilibrium. Inertia is Newton’s first law of motion.  This law word for word is “Every object continues in a state of rest or uniform speed in a straight line unless acted on by a nonzero net force.” That was my understanding of inertia before we had the demonstration of the hovercraft. However, after the hovercraft demonstration I learned that inertia is simply the property of laziness in all objects. I also learned that net force is multiple pushes or pulls and that when the net force equals zero the object is in equilibrium. Equilibrium is when opposite forces create a force of zero and everything is in balance.

Based on this lab, acceleration depends on the mass of an individual or an object. Naeem was much more difficult to slow down than Margaret Anne was not because he weighs more but because he has more mass.

After performing this lab, I would expect for constant velocity to happen in the middle stage of an objects movement. 

http://www.youtube.com/watch?v=JIwcPhjDdpY 

In physics this year, I expect to learn a variety of things including how credit card machines read your information when you swipe your card, what properties of light allow us to see, and the causes of the ocean tides. I think studying physics is significant because in general it will help us understand the world around us and unlike most sciences it will help us understand the properties behind everyday occurrences. It’s also important to learn physics because it will help us be more aware of our surroundings. Lastly, physics can open up a wide range of interests that a student might want to look into more specifically. I definitely have a number of questions about physics considering I have never taken physics class but I have a few main questions that I hope will be answered by the end of this course. The first question again involves ocean tides. I live on the beach so I’ve always been curious about the tides but more specifically the size of the waves. I know that waves tend to be bigger when there is a storm or strong wind but what else affects the wave size? Another question I have involves the class itself. Looking at all titles of the units I’m just curious as to how we will be testing these different subjects. For instance, how will we be testing an ice skaters spin?