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Q1-3. 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.

Asteroids under gravity

  

1. Which one of the following best describes the relative sizes of the forces of gravity FX and FY acting on the asteroids?

  • A. FX is zero, FY is non-zero.
  • B. FX > FY (and both are non-zero).
  • C. FX < FY (and both are non-zero).
  • D. FX = FY (and both are non-zero).

2. If the mass of both asteroids is doubled, how does this affect FY?

  • 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 FY?
  • 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.

5-10. 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'.

satellite in orbit

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?

  • A.  
GM = mv2
r2 r
  • B.  
GM = mv
r2 r2
  • C.  
GMm = mv2
r2 r
  • D.  
GMm = mv
r2 r2

8. Which of the following correctly states the value of v2?

  • A.   
 v2 = GM
r2
  • B.  
v2 = GMm
r2
  • C.  
v2 = GM
r
  • D.  
v2 = GMm
r2

9. The satellite orbits the planet once every 10,000 seconds. What is the frequency of this orbit?

  • A. 104 Hz
  • B. 10-4 Hz
  • C. 103 Hz
  • D. 10-3 Hz

10. if the radius of the orbit is 107 m, what is the velocity of the satellite?

  • A. 2π x 107 ms-1
  • B. 2π x 103 ms-1
  • C. 104 ms-1
  • D. 103 ms-1