The Top 10 Uses of Physics During the Summer
1)
Let’s say it’s a regular summer day and you are
planning to go to the beach (and you live near the beach). So, you wake up and make a smoothie for
breakfast. This smoothie would not be a possibility without physics! There is a
motor in the blender, which allows the blender to work. How does this motor
work?
Electrical
energy is converted to mechanical energy. A current carrying wire feels a fore
in a magnetic field. That is the underlying principle. Then, the force the loop
feels will cause a torque. This torque will cause a spin and will cause the
blender to rotate.
2)
While drinking your smoothie, you turn on the
television. Even this simple
gesture involves physics. All houses are wired in a parallel circuit. A parallel circuit has electrical devices connected to the same two
points. The pathway for current from one end of the battery to the other is
completed if only one device is running rather than all the devices in the
circuit. The more appliances added to the circuit the resistance
decreases, the current increases, the brightness remains constant and when one device
isn’t working or being the used the rest are not affected. Households use
parallel circuits because it is more efficient. Parallel circuits allow
households to run multiple devices without running other devices unlike series
where it is all or nothing. This is why you can turn the television on without
turning on the rest of the devices in the house. The only major disadvantage to
parallel circuits is the heat factor. The more current and less resistance
there is (which happens the more devices are on), there is high heat, which
could potentially turn into a fire. A fuse/circuit breaker prevents this from
happening. A fuse is used to prevent the current from getting to this dangerous
level. The fuse melts and snaps turning the circuit off. A fuse is used in
parallel circuits but it is set up in series.
3)
If you are planning
on going to the beach, it would be wise to check the tides before you went. 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.
To the left 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.
To the right 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.
So, before going to the beach, it is key to know
whether it will be high tide or low tide because it is constantly changing.
4)
You decide to pack a
lunch for the beach. So, you cut up watermelon to put in a ceramic bowl and put
plastic wrap to cover the watermelon. This plastic wrap doesn’t just magically
stick to the bowl. Thanks to
physics we know why exactly, the plastic wrap sticks to the bowl. The plastic
wrap is charged by friction and when brought near the bowl, the bowl polarizes.
The positive charges in the bowl move close to the negative plastic wrap and
the negative charges in the bowl move away from the plastic wrap. The distance
between the opposite attractive chargers is smaller than the distance between
the like repelling charges. Coulomb’s law states that the force between any two
charges are inversely proportional to the distance. F=kq1q2/d^2. Because there is a greater
distance between the repulsive forces, the forces between them will be less
than closer attractive forces. Therefore, the plastic sticks to the ceramic
bowl. [INSERT IMAGE]
5)
Finally you’re on the
road to the beach. You are talking to your friend and realize there is a stop
sign. You stop suddenly because you weren’t paying close enough attention.
Luckily, all cars have headrests and seatbelts. When the car is moving,
everything else in the car is also moving. If the car comes to an abrupt stop,
everything keeps moving that is not attached to the car. We know this because
according to Newton’s First Law, when an object is in motion it will want to
stay in motion unless a force is acted upon it. Therefore, your head and your
body will want to keep moving forward. The seatbelt prevents your body from
continuing forward through the car. Your head pulls backward naturally and
would continue moving backwards, however the headrest acts as a force to
prevent your head from continuing backwards. Thanks to car designers knowledge
on physics and Newton’s First Law of Motion, you’re safe and are able to
continue on to the beach.
6)
You continue on your
way and approach a stoplight. How does this stoplight work? Well, physics makes
this answer simple. In the pavement, there is a loop of wire. When the car,
which is magnetic, moves over the wire, it changes the magnetic field of the
loop. This change induces voltage, which causes a current. [Mechanical energy
is converted to electrical energy.]This current is a signal to the stoplight to
change allowing you to continue on to the beach.
7)
Finally you get to
the beach, you carry the lunch cooler to the beach. Although this may feel
challenging and it may feel like you are doing a lot of work, however, in
physics terms, you are actually doing NO work. The force, which is the cooler,
being pulled down by gravity is not parallel to the horizontal distance the
cooler is moving. Work is the effort exerted on something that will change its
energy. Work equals force times distance. [Work=Force X
Distance] Work is
measured in Joules. The force and distance must be parallel to one another in
order for there to be work done.
8)
You and your friends
decide to race on the beach. The fundamentals of running comes from physics
too. All runners bend their legs when they run because they are moving their
legs closer to their axis of rotation (their hips). We know this is important
from the property of rotational inertia. Rotational inertia is the property of
an object to resist changes in spin or rotation. It is not based upon the mass
of an object, rather where that mass is located or how it is distributed (how
far it is from the axis of rotation). Therefore, runners bring their mass
closer to the axis of rotation to lower their rotational inertia. The farther
away from the axis of rotation, the higher rotational inertia an object has.
9)
After a long day at
the beach, the typical summer afternoon storms rolls in. What causes lightning?
Lightning is a good example of induction. Charging by induction takes place
during thunderstorms. The clouds are negatively charged by friction and the
clouds positively induce the ground. The attractive forces eventually
become strong enough to produce lightning. Therefore lightning starts from the
ground, travels upward and then recedes toward the ground. (Click on image for a closer view.)
10)
On your way back into
town, you decide to drive through downtown (Beaufort), the storm hasn’t reached
downtown yet and people are walking on the streets and horses are pulling
buggies filled with tourists. How can a horse possibly do this? 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.
Therefore, the horse is able to pull the buggy forward.
