10 minutes maximum! Can you do it in 5? 
Q13. The diagram shows 2 asteroids. Both asteroids are attracted to each other by the force of gravity. Asteroid X is much larger and more massive than asteroid Y.


1. Which one of the following best describes the relative sizes of the forces of gravity F_{X} and F_{Y} acting on the asteroids?
 A. F_{X} is zero, F_{Y} is nonzero.
 B. F_{X} > F_{Y} (and both are nonzero).
 C. F_{X} < F_{Y} (and both are nonzero).
 D. F_{X} = F_{Y} (and both are nonzero).


2. If the mass of both asteroids is doubled, how does this affect F_{Y}?
 A. The force is the same.^{}
 B. The force is 2 x larger.^{}
 C. The force is 4 x larger.^{}
 D. The force is 8 x larger.


3. If the original asteroids in the diagram are moved 4 times as far apart, how will this affect the original value of F_{Y}?
 A. The force is 2 x smaller^{}.
 B. The force is 4 x smaller^{}
 C. The force is 8 x smaller.^{}
 D. The force is 16 x smaller.


4. The acceleration of gravity, 'g' is defined as .....
 A. the force of gravity acting per unit mass.
 B. the force of gravity acting per unit time.
 C. the change in velocity per unit mass.
 D. the change in velocity per unit volume.


510. A small satellite of mass m is in orbit around a large planet of mass M at a distance of r from the centre of the planet.
The gravitational constant is 'G'. 

5. The value of the acceleration of gravity 'g' acting on the satellite is calculated. What is these statements is true?
 A. The value of g is independent of the value of r.
 B. The value of g is independent of the value of M.
 C. The value of g is independent of the value of G.
 D. The value of g is independent of the value of m.


6. The satellite moves closer to the planet to take images of the surface. How will this affect g and v, the velocity of the satellite in orbit?

g 
v 
A 
increases 
decreases^{} 
B 
increases^{} 
increases 
C 
stays the same 
increases 
D 
decreases^{} 
stays the same 


7. Which of these formulas can be used to calculate the value of the orbital velocity v?

GM 
= 
mv^{2} 
r^{2} 
r 

GM 
= 
mv 
r^{2} 
r^{2} 

GMm 
= 
mv^{2} 
r^{2} 
r 

GMm 
= 
mv 
r^{2} 
r^{2} 


8. Which of the following correctly states the value of v^{2}?

v^{2} 
= 
GM^{} 
r^{2} 

v^{2} 
= 
GMm 
r^{2} 

v^{2} 
= 
GM^{} 
r 

v^{2} 
= 
GMm 
r^{2} 


9. The satellite orbits the planet once every 10,000 seconds. What is the frequency of this orbit?
 A. 10^{4} Hz
 B. 10^{4} Hz
 C. 10^{3} Hz
 D. 10^{3} Hz


10. if the radius of the orbit is 10^{7} m, what is the velocity of the satellite?
 A. 2π x 10^{7} ms^{1}
 B. 2π x 10^{3} ms^{1}
 C. 10^{4 }ms^{1}
 D. 10^{3} ms^{1}


