1. The gravitational force on an object of mass m a distance r from the centre of the Earth is given by. The potential energy of the object is taken to be zero when the object is an infinite distance from the Earth. When it is a distance r from the centre of the Earth its potential energy is (a)negative (b)positive (c)not enough information to tell

2. The gravitational force on an object of mass m a distance r from the centre of the Earth is given by. The potential energy of the object is taken to be zero when the object is an infinite distance from the Earth. When it is a distance r from the centre of the Earth its potential energy is (a) U(r) = GmM E /r (b) U(r) =- GmM E /r (c) U(r) = mgr (d) U(r) = -GmME/r 2

3. At the right is the gravitational potential energy diagram for a meteor at a distance r from the centre of the Earth. If the meteor started with almost zero velocity when it was far from the Earth, which of the following diagram best represents its kinetic energy K(r) as it approaches the Earth? (a)(b)

4. The potential energy of an object of mass m a distance r from the centre of the earth is given by U(r) = -GmM E /r. Which of the following curves best represents U(r)?

5. The gravitational potential energy of a satellite is chosen to be zero when it is an “infinite” distance from the earth. Which of the following expressions best describes its potential energy when it is a distance r above the center of the earth? Be sure you know why the wrong ones cannot be right, as well as which one is correct.

6. A rocket ship (mass m) is shot vertically from the surface of the Earth (mass M) with a velocity v that it maintains for the short time until the fuel is gone. Which of the following gives the best way to calculate its maximum height h above the surface of the Earth? (R E is the radius of the Earth.) (a) (c) (b) (d) (e)