If the distance between two objects is increased by two times, the gravitational force between them will
- A.remain same
- B.increase by two times
- C.decrease by two times
- D.decrease by four times
Correct answer
Explanation
The correct answer is D, decrease by four times. Gravitational force varies inversely with the square of the distance, so doubling the distance cuts the force to one-fourth.
Newton's law of universal gravitation states that the force between two masses is F = G m1 m2 / r², where r is the distance between their centres and G is the universal gravitational constant, about 6.67 × 10⁻¹¹ N m² kg⁻². If r becomes 2r, the denominator becomes 4r², so the new force is F/4. In the same way, tripling the distance makes the force one-ninth, and halving it makes the force four times stronger. This inverse-square rule also explains why gravity weakens as one moves far above the Earth's surface.
A is wrong because the force depends on distance and must change. B is wrong because moving objects apart weakens gravity, it never strengthens it. C is wrong because that would be true only if force varied with distance itself, not with its square.
Exam tip: F ∝ 1/r²: distance ×2 gives force ÷4; distance ×3 gives force ÷9; distance ÷2 gives force ×4.
Practice Questions
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- A.Refractometer
- B.Galvanometer
- C.Viscometer
- D.Diffractometer
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- A.multiple refraction of sound.
- B.multiple reflection of sound.
- C.single refraction of sound.
- D.single reflection of sound.
Show answer
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- A.Charges can be added
- B.Charge is conserved
- C.Charge on a body is always an integral multiple of an electron or a proton charge
- D.Charges can be created and destroyed in an isolated system
Show answer
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Read the full explanation →Which of the following organelles have their own DNA and ribosomes?
- A.Endoplasmic reticulum and Golgi bodies
- B.Mitochondria and Chloroplast
- C.Endoplasmic reticulum and cytoskeleton
- D.Cell wall and nucleolus
Show answer
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Read the full explanation →Which one of the following statements is NOT correct ?
- A.All proteins are enzymes
- B.Mostly enzymes are proteins
- C.All fats are energy rich compounds
- D.Glucose is a common carbohydrate
Show answer
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