Gravitation Questions and Answers Part-2

1. The gravitational force between two point masses \[m_{1}\] and \[m_{2}\] at separation r is given by\[F=k\frac{m_{1}m_{2}}{r^{2}}\]   . The constant k
a) Depends on system of units only
b) Depends on medium between masses only
c) Depends on both (a) and (b)
d) Is independent of both (a) and (b)

Answer: a
Explanation: k represents gravitational constant which depends only on the system of units

2. The distance of the centres of moon and earth is D. The mass of earth is 81 times the mass of the moon. At what distance from the centre of the earth, the gravitational force will be zero
a) \[\frac{D}{2}\]
b) \[\frac{2D}{3}\]
c) \[\frac{4D}{3}\]
d) \[\frac{9D}{10}\]

Answer: d

3.Who among the following gave first the experimental value of G
a) Cavendish
b) Copernicus
c) Brook Teylor
d) None of these

Answer: a
Explanation: Cavendish

4. The mass of the moon is \[7.34\times10^{22}kg\]   and the radius is \[ 1.74\times10^{6}m\]   . The value of gravitation force will be
a) 1.45 N/kg
b) 1.55 N/kg
c) 1.75 N/kg
d) 1.62 N/kg

Answer: d

5.The centripetal force acting on a satellite orbiting round the earth and the gravitational force of earth acting on the satellite both equal F. The net force on the satellite is
a) Zero
b) F
c) \[F\sqrt{2}\]
d) 2 F

Answer: b
Explanation: Actually gravitational force provides the centripetal force

6. Reason of weightlessness in a satellite is
a) Zero gravity
b) Centre of mass
c) Zero reaction force by satellite surface
d) None

Answer: c
Explanation: Zero reaction force by satellite surface

7. Mass M is divided into two parts xM and (1 - x)M . For a given separation, the value of x for which the gravitational attraction between the two pieces becomes maximum is
a) \[\frac{1}{2}\]
b) \[\frac{3}{5}\]
c) 1
d) 2

Answer: a

8. The force of gravitation is
a) Repulsive
b) Electrostatic
c) Conservative
d) Non-conservative

Answer: c
Explanation: The force of gravitation is Conservative

9.The gravitational force \[F_{g}\] between two objects does not depend on
a) Sum of the masses
b) Product of the masses
c) Gravitational constant
d) Distance between the masses

Answer: a
Explanation: Sum of the masses

10. Two sphere of mass m and M are situated in air and the gravitational force between them is F. The space around the masses is now filled with a liquid of specific gravity 3. The gravitational force will now be
a) F
b) \[\frac{F}{3}\]
c) \[\frac{F}{9}\]
d) 3 F

Answer: a
Explanation: Gravitational force does not depend on the medium