In unit two we started off learning about Newton’s second
law of motion, which states that acceleration is directly proportional to force
and inversely proportional to mass. This law can be read as a=f net / mass.
With this law it was also necessary to learn that weight = (mass)(gravity).
Weight is measured in newtons while mass is measured in kilograms. Next we
learned about free fall excluding air resistance. An object in free fall, falls
with an acceleration of 9.8 m/s^2. Knowing this, we learned how to calculate
how long it is going to take for something to fall simply by knowing the height
it falls from or vise versa. For example, when we calculated the height of 3rd
Anderson. After dropping a ball multiple times and taking the average time it
took for the ball to reach the ground, we calculated the height. We took our
average time and plugged it into the distance equation, d=1/2gt^2 and solved
for d. This brought us to the approximate height of 3rd Anderson.
During free fall an object is constantly accelerating at a rate of 9.8m/s^2
until it reaches the ground.
Projectile motion is when something is pushed with a force
and is projected through the air. For example, an airplane dropping a box. When
an airplane drops a box the box is going to fall at 9.8 m/s^2 vertically, but
the horizontal speed is going to remain constant through the reasoning of
Newton’s first law. In order to find the vertical distance or time you are
going to use the same distance equation that you would use for free fall,
d=1/2gt^2. However for the horizontal velocity of an object you are going to use
velocity=distance/time. For example, if you wanted to know how far in advance a
plane should drop a box in order to reach a certain target you are going to use
the formula v=d/t and solve for d.
After learning about projectile motion we learned about
objects falling through the air. An object falling through air and an object in
free fall are completely different. An object falling through the air is going
to increase velocity and accelerate less and less until it reaches a point of
constant velocity and zero acceleration. The object is going to reach a
constant velocity when the net force of the object is zero. When an object
falls, the force of gravity pulls it down according to its weight. The faster
the velocity of the object the larger the force of air is going to be on the
object. The object falling through the air is going to keep increasing its
velocity until the force of air is large enough to subtract to zero when in
accordance with the force of weight. An object with a greater weight is going
to have to travel faster in order to reach a constant velocity because the
force of air is going to need to be greater in order to reach a net force of
zero.
Lastly, we learned about throwing things up at an angle.
When something is thrown up at an angle you can calculate how much time it
spends in the air by using the force of gravity acting on the force exerted on
the object. When you find the time, you can calculate how far the object went.
Throughout the flight of the object the horizontal velocity is going to stay
the same and the vertical acceleration is going to remain at 9.8 m/s^2 at all
times, even when the objects vertical velocity is at zero. At the peak of the
objects path the velocity is going to be only the horizontal since the vertical
velocity is going to be at zero. All calculations pertaining to the vertical
velocity or time can be found using the formula d=1/2gt^2. All calculation pertaining
to the object horizontal motion can be found with v=d/t.
