Gravitation – Objective Questions

Page 4 • Multi-Concept & Numerical Traps (With Explanations)

                                                

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Question 22

A satellite orbits Earth at a height equal to Earth’s radius. The ratio of its orbital speed to escape speed at that point is:

A) 1 : √2 B) 1 : 2 C) √2 : 1 D) 1 : 1

Correct Answer: A) 1 : √2

Explanation:

At distance r = 2R:
Orbital speed v = √(GM/r)
Escape speed v_e = √(2GM/r)
⇒ v : v_e = 1 : √2

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Question 23

If acceleration due to gravity on a planet is 4g and its radius is twice that of Earth, its mass compared to Earth is:

A) same B) twice C) four times D) sixteen times

Correct Answer: D) sixteen times

Explanation:

g = GM/R² ⇒ M ∝ gR² Given g_p = 4g, R_p = 2R
M_p = 4 × (2)² = 16 times Earth’s mass.

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Question 24

At what height above Earth’s surface will g become half of its surface value?

A) R/2 B) R C) (√2 − 1)R D) 2R

Correct Answer: C) (√2 − 1)R

Explanation:

g_h = g(R² / (R + h)²) = g/2 ⇒ (R + h)² = 2R² ⇒ h = (√2 − 1)R

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Question 25

Two satellites A and B revolve around Earth in circular orbits with radii R and 4R. The ratio of their time periods is:

A) 1 : 2 B) 1 : 4 C) 1 : 8 D) 1 : 16

Correct Answer: C) 1 : 8

Explanation:

Time period T ∝ r^3/2
T_B/T_A = (4R/R)^3/2 = 8

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Question 26

If Earth stops rotating, which of the following remains unchanged?

A) Weight at equator B) Weight at poles C) Shape of Earth D) Value of g at equator

Correct Answer: B) Weight at poles

Explanation:

Centrifugal force is zero at poles even now, so stopping rotation does not affect weight at poles.

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Question 27

Gravitational potential energy of a body near Earth’s surface is taken as:

A) zero B) positive C) negative D) infinite

Correct Answer: C) negative

Explanation:

Reference level is zero at infinity. Since body is bound to Earth, potential energy is negative.

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Fast Elimination Tip

Whenever powers of R appear, immediately write proportionality. It avoids long calculations.

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Objective Questions • Page 4 Completed ✅

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• Gravitation – Part 1
• Gravitation – Part 2
• Gravitation – Part 3
• Gravitation – Part 4
• Gravitation – Part 5
• Gravitation – Part 6
• Gravitation – Part 7
• Gravitation – Part 8
• Gravitation – Part 9
• Gravitation – Part 10
• Gravitation – Part 11
• Gravitation – Part 12
• Gravitation – Part 13
• Gravitation – Part 14
• Gravitation – Part 15
• Gravitation – Part 16
• Gravitation – Part 17
• Gravitation – Part 18
• Gravitation – Part 19
• Gravitation – Part 20
• Gravitation – Part 21
• Gravitation – Part 22
• Gravitation – Part 23
• Gravitation – Part 24
• Gravitation – Part 25
• Gravitation – Part 26
• Gravitation – Part 27
• Gravitation – Part 28
• Gravitation – Part 29
• Gravitation – Part 30
• Gravitation – Part 31
• Gravitation – Part 32
• Gravitation – Part 34
• Gravitation – Part 35
• Gravitation – Part 36
• Gravitation – Part 37
• Gravitation – Part 38
• Gravitation – Part 39
• Gravitation – Part 40
• Gravitation – Part 41
• Gravitation – Part 42

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