Free Gravitation MCQs with Answers

171. The mean density of earth is:

• A. 5462 kgm-3
• B. 5462 gm-3
• C. 5462 kgm3
• D. None of these

Explanation: A is correct. It is a fact that the mean density of Earth is approximately 5.5 x 103 kgm-3 .

172. Acceleration due to gravity is given by the equation:

• A. Option A
• B. Option B
• C. Option C
• D. Option D

Explanation: B is correct as per the derived formula. g= GM/R2 .

173. Value of acceleration due to gravity gh at height h is given by the equation:

• A. Option A
• B. Option B
• C. Option C
• D. Option D

Explanation: The Explanation for this question will be added soon!

174. The radius of earth is:

• A. 6400 m
• B. 6400 km
• C. 6400 cm
• D. 6400 dm

Explanation: B is correct. It is a fact that the radius of the Earth is 6400 km.

175. It is a measure of the reluctance of an object to change its state of motion when force is applied:

• A. Mass
• B. Inertial mass
• C. Gravitational mass
• D. None of the above

Explanation: B is correct. Inertia is the measure of the reluctance of an object to change its state of motion when force is applied according to the 1st law of motion.

176. Acceleration due to gravity at a depth x is given as:

• A. Option A
• B. Option B
• C. Option C
• D. Option D

Explanation: A is the correct option as per the derived formula.

177. When a body is lifted to twice earth's radius above the surface of the earth, the value of g decreases by:

• A. Two times
• B. Three times
• C. Six times
• D. Nine times

Explanation: D is correct. g= GM/r 2 , as the distance is increased from R to 3R so g' will be =GM/9r2 As a result g' will be 9 times less than g.

178. The frequency of rotation for artificial gravity is:

• A. Option A
• B. Option B
• C. Option C
• D. Option D

Explanation: C is correct as per the derived formula, formed by using centripetal acceleration.

179. Freely falling bodies are in a state of:

• A. Rest
• B. Static equilibrium
• C. Dynamic equilibrium
• D. Weightlessness

Explanation: Dis correct. Freely falling bodies are already accelerating at a 9.81 m/s2 so experience no additional force by Earth and hence feel weightless.

180. What is produced by spinning the spaceship around its own axis with a certain frequency which can provide centripetal force equal to the force of gravity at that point?

• A. Weightlessness
• B. Artificial gravity
• C. Vacuum
• D. None of the above

Explanation: B is correct. By spinning the spaceship around its own axis with a certain frequency which can provide centripetal force equal to the force of gravity, we can produce artificial gravity which reduces the feeling of weightlessness.