1. The gravitational potential at the Earth's surface is about -60 MJ kg-1 . The work done in lifting a 2kg mass into deep space away from the Earth is therefore:

  • A. +60MJ
  • B. -60 MJ
  • C. +120MJ
  • D. -120MJ

2. A planet that is twice as massive as the Earth but only has 1/2 the radius will therefore have a gravitational potential at the surface of about ...

  • A. -15 MJ kg-1
  • B. -60 MJ kg-1
  • C. -120 MJ kg-1
  • D. -240 MJ kg-1

3. Which of these statements about the magnitude of the gravitational field strength at any point is true?

  • A. gravitational field strength = gravitational potential gradient
  • B. gravitational field strength = gravitational force gradient
  • C. gravitational field strength gradient = gravitational potential
  • D. gravitational field strength gradient = gravitational force

4. Which of these diagrams best shows the shape of equipotential surfaces around two identical binary stars?

equipotential surfaces aound binary stars

5. Two objects of mass m and 2m are located at distances r and 2r from a planet as shown.

planet with 2 satellites in orbit

The ratio     gravitational potential at m     is:
gravitational potential at 2m
  • A. 2
  • B. ½
  • C. 4
  • D. ¼

6. A satellite lands on a small spherical asteroid. To escape the pull of gravity of the asteroid on the return journey, the satellite needs to be launched with a certain escape velocity. Data for the launch is available, including:

  • I. The mass of the asteroid.
  • II. The mass of the satellite.
  • III. The radius of the asteroid.
Ceres (public domain picture)
image: nasa.gov
Which of these 3 factors affects the escape velocity of the satellite?
  • A. I and II
  • B. I and III
  • C. II and III
  • D. All three statements

7. To stay in a circular orbit of radius r around the Earth, a satellite of mass m has a potential energy of Ep. If the satellite now moves into a higher orbit of radius 2r, the potential energy..

A. increases by
B. decreases by
C. increases by
D. decreases by

8. When in orbit, how is the gravitational potential energy (Ep) of a satellite related to the kinetic energy (Ek)?

  • A. Ep= Ek
  • B. Ep= 2Ek
  • C. Ep = - Ek
  • D. Ep = - 2Ek

9. As the satellite moves into a higher orbit, how does the total energy and the kinetic energy change?

total energy
kinetic energy