In discussions of satellites by laymen, one often hears questions such as "What keeps the satellite moving in its orbit?" and "What keeps the satellite up?" How do you answer these questions? Are your answers also applicable to the moon?

During an actual interview for a college teaching position in physics, several candidates said that the earth does not fall into the sun because the gravitational pull from the outer planets prevents it from doing so. If you were on the interview committee, would you hire any of these candidates? Explain your reasoning.

If there is a net force on a particle in uniform circular motion, why doesn't the particle's speed change?

If there is a net force on a particle in uniform circular motion, why doesn’t the particle’s speed change?

On your electrical "power" bill, you are charged for kilowatthours ( $\mathrm{kWh}$ ). Is this really a power bill? What kind of quantity is the kilowatt-hour?

On a separate sheet of paper, answer the questions below. Make sure you read carefully and answer all parts of the questions. Speculate on the strength of the arguments against many women accused of witchcraft during the inquisition in the sixteenth and seventeenth centuries.

An object is released from rest at the top of a ramp. If the ramp is frictionless, does the object’s speed at the bottom of the ramp depend on the shape of the ramp or just on its height? Explain. What if the ramp is not frictionless?

Does an object's speed at the bottom of a frictionless ramp depend on the shape of the ramp or just on its height? Explain. What if the ramp is not frictionless?

Hydroelectric energy comes from gravity pulling down water through dams in rivers. Explain how such energy is really just a form of solar energy by tracing how the sun's energy is able to get the water from the ocean to the reservoir behind the dam.

If the movie "super gorilla" King Kong beats his chest on a frozen frictionless lake, will he go backward? Why?

In a zero-gravity environment, can a rocket-propelled spaceship ever attain a speed greater than the relative speed with which the burnt fuel is exhausted?

A machine gun is fired at a steel plate. Is the average force on the plate from the bullet impact greater if the bullets bounce off or if they are squashed and stick to the plate? Explain.

At the highest point in its parabolic trajectory, a shell explodes into two fragments. Is it possible for both fragments to fall straight down after the explosion? Why or why not?

An egg is released from rest from the roof of a building and falls to the ground. As the egg falls, what happens to the momentum of the system of the egg plus the earth?