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 shows the shape of equipotential surfaces around two identical binary stars?


Two small masses m and 2m are located at distances r and 2r from a much larger planet as shown.


5. The ratio
gravitational potential at m 
gravitational potential at 2m 
is


6. To escape the pull of a small spherical asteroid, a satellite needs to be launched with a certain escape velocity. Which of these 3 factors affects the escape velocity of the satellite?
I 
The mass of the asteroid. 
II 
The mass of the satellite. 
III 
The radius of the asteroid. 


image:
nasa.gov 
 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 E_{p}. If the satellite now moves into a higher orbit of radius 2r, the potential energy..


8. When in orbit, how is the gravitational potential energy (E_{p}) of a satellite related to the kinetic energy (E_{k})?
 A. E_{p}= E_{k}
 B. E_{p}= 2E_{k}
 C. E_{p} =  E_{k}
 D. E_{p} =  2E_{k}


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

total energy 
kinetic energy 
A 
increases 
decreases 
B 
increases 
increases 
C 
decreases 
constant 
D 
decreases 
decreases 



