Physics Questions Help

I need to answer the following questions with some explanation (simple terms please).

State 2 reasons why a rock projected with a slingshot will go faster if the rubber is stretched an extra distance.

If a mouse and an elephant both run with the same kinetic energy, can you say which is running faster? Explain in terms of the equation for kinetic energy.

An astronaut in full space gear climbs a vertical ladder on the earth. Later, the astronaut makes the same climb on the moon. In which location does the gravitational potential energy of the astronaut change more? Explain.

Relative to the ground below, how many joules of potential energy does a 1000 N boulder have at the top of a 5 meter ledge? If it falls, with how much kinetic energy will it strike the ground? What will be its speed on impact?

A hammer falls off a rooftop and strikes the ground with a certain kinetic energy. If it feel from a roof that was four times higher, how would its kinetic energy of impact compare? Its speed of impact? (Neglect air resistance.)

I'm a junior in high school, so if you could answer these as simplistically as possible, that would be great.

1. One reason why the rock will go faster is because as the rubber is stretch an extra distance, it will increase in potential energy. Assuming all the potential energy is transform into kinetic energy when the slingshot is release, the rock will go faster since the mass of the rock stay the same. Let say U is the potential energy, then 2U is the energy from the extra distance. U = (1/2)mv^2, then 2U=(1/2)mv^2. Solve for v and you will see that the v for 2U is greater. No idea about the second reason though.

2. Yes. The equation for kinetic energy is (1/2)mv^2. Since the kinetic energies are equal, you can set the equation for the elephant equal to the equation of the mouse.
(1/2)Mv^2=(1/2)mv^2; where M=mass of elephant and m=mass of mouse