Answer:
C
Explanation:
Generally, the speed of light slows down when passing through a medium that is not a vacuum. This is not always the case, but I will be ignoring the rare/exotic exceptions. Light has a harder time traveling through solids and liquids than it does with gases.
First I’ll show you this standard derivation using conservation of energy:
Pi=Kf,
mgh = 1/2 m v^2,
V = sqrt(2gh)
P is initial potential energy, K is final kinetic, m is mass of object, h is height from stopping point, v is final velocity.
In this case the height difference for the hill is 2-0.5=1.5 m. Thus the ball is moving at sqrt(2(10)(1.5))=
5.477 m/s.
True
In fact, the weight of an object on the surface of the Earth is given by:

where m is the mass of the object and

is the gravitational acceleration on Earth's surface. If we use the mass of the object, m=3.0 kg, we find
It is powered by the Earth's rotation and the moon gives a little boost.