Free Gravitation MCQs with Answers

111. There is a body lying on the surface of the Earth and suppose the Earth suddenly loses its power of attraction then:

• A. The mass of the body will reduce to zero
• B. The weight of the body will reduce to zero
• C. Both will reduce to zero
• D. It becomes infinity

Explanation: Statement B is correct. Weight is the force with which gravity pulls an object toward the center of the Earth (or any celestial body). If the Earth were to lose its gravitational attraction, the object would no longer experience a gravitational force, and its weight would become zero.

112. Which of the following is the evidence to show that there must be force acting on Earth and directed towards the Sun?

• A. Deviation of the falling bodies towards east
• B. Revolution of the Earth round the Sun
• C. Phenomenon of day and night
• D. Apparent motion of Sun round the Earth

Explanation: Option B is a key piece of evidence. The fact that Earth revolves around the Sun is a result of gravitational attraction between the Earth and the Sun. According to Kepler's laws of planetary motion and Newton's law of universal gravitation, there must be a force acting on Earth directed towards the Sun to keep it in orbit.

113. If the radius of Earth were to shrink by one percent, its mass remaining the same, the acceleration due to gravity on the Earth's surface would:

• A. Decrease
• B. Remain unchanged
• C. Increase
• D. None of these

Explanation: Option c is correct. As explained earlier, a 1% decrease in the radius leads to an increase in the gravitational acceleration at the Earth's surface.

114. In planetary motion:

• A. The angular speed remains constant
• B. The total angular momentum remains constant
• C. The linear speed remains constant
• D. Neither the angular momentum nor angular speed remains constant

Explanation: Statement B is close to being true. According to Kepler's laws, the total angular momentum of a planet remains constant during its motion around the Sun. The law of conservation of angular momentum states that in the absence of external torques, the total angular momentum of a system remains constant.

115. The escape velocity of an object projected from the surface of a given planet is independent of:

• A. The mass the object
• B. The direction of projection
• C. The mass of the planet
• D. Radius of the planet

Explanation: The escape velocity is independent of the mass of the object. This is a fundamental principle based on the conservation of energy. The escape velocity is the minimum velocity an object must attain to break free from the gravitational influence of a celestial body. The mass of the object cancels out in the escape velocity formula. Therefore, the escape velocity is the same for objects of different masses, assuming the same initial and final positions.

116. The southern Hemisphere of Earth is "up side down", but the people living there do not fall off the Earth because:

• A. Earth attracts every body nearly towards its centre
• B. Their weight is zero
• C. Their weight is infinite
• D. The value of g is zero in the Southern Hemisphere

Explanation: This option is correct. The force of gravity acts toward the center of the Earth. Regardless of where you are on the Earth's surface, gravity is pulling you toward its center. This gravitational force is what keeps people, and everything else, grounded on the Earth.

117. Newton's law of gravitation is universal because:

• A. It is always attractive
• B. It acts on all heavenly bodies and particles
• C. It acts on all the masses at all the distances and is not affected by the medium
• D. All of the above

Explanation: The correct answer is "All of the above" because options (a), (b), and (c) are all accurate descriptions of why Newton's law of gravitation is considered universal. The law is always attractive, it applies to all heavenly bodies and particles, and it acts on all masses at all distances, unaffected by the medium through which it operates.

118. As we go from the equator to the poles, the value of "g":

• A. Remains the same
• B. Decreases
• C. Increases
• D. Decreases upto latitude of 45o

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

119. G, which is used in universal law of gravitation, is actually:

• A. Force of gravitation
• B. Constant of gravitation
• C. Gravitational acceleration
• D. Gravitational attraction

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

120. According to the law of gravitation the attraction between the two bodies increases when distance between them is:

• A. Increased
• B. Decreased
• C. Kept the same
• D. Nothing can be said

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