The kinetic energy of a book on a shelf is equal to the work done to lift the book to the shelf is false. The kinetic energy on the shelf is zero because it is not in action.
Answer:
The height is 3.1m
Explanation:
Here we have a conservation of energy problem, we have a conversion form eslastic potencial energy to gravitational potencial energy, so:

then we have only gravitational potencial energy when the ball is at its maximun height.

because all the energy was transformed Eg=Ee

searching the web, the mass of a ping pong ball is 2.7 gr in average. so:

The answer & explanation for this question is given in the attachment below.
Answer:
True
The escape speed from the Moon is much smaller than from Earth.
Explanation:
The escape speed is defined as:
(1)
Where G is the gravitational constant, M is the mass and r is the radius.
The mass of the Earth is
and its radius is 
Then, replacing those values in equation 1 it is gotten.
For the case of the Moon:
Hence, the escape speed from the Moon is much smaller than from Earth.
Since it has a smaller mass and smaller radius compared to that from the Earth.
Answer:
B. 0.16 m
Explanation:
The vertical distance by which the player will miss the target is equal to the vertical distance covered by the dart during its motion.
Since the dart is thrown horizontally, the initial vertical velocity is zero:

While the horizontal velocity is

The horizontal distance covered is

Since the dart moves by uniform motion along the horizontal direction, the time it takes for covering this distance is

along the vertical direction, the motion is a uniformly accelerated motion with constant downward acceleration g=9.8 m/s^2, so the vertical distance covered is given by
