Assertion (A): In a free fall, a heavy object falls faster than a light object. Reason (R): Acceleration due to gravity is same for all objects. MCQ with Answer and Explanation

Assertion (A): In a free fall, a heavy object falls faster than a light object. Reason (R): Acceleration due to gravity is same for all objects.
A. A is true, R is false
B. A is false, R is true
C. Both A and R true, R is correct explanation
D. Both A and R true, R not correct explanation
Answer: Option B
Solution (By JKExamLibrary)
In vacuum, all objects fall at same rate. A is false. R is true. So C correct.

This question belongs to: Science Physics

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Question #1 Report Error
The weight of a body is maximum at
A. Centre of Earth
B. Same everywhere
C. Equator
D. Poles

Correct Answer: Option D


Explanation:
g_pole > g_equator due to less centrifugal effect and Earth's oblateness. At centre g=0, weightless. So weight max at poles.

This question belongs to: Science Physics
Question #2 Report Error
The universal law of gravitation states that the force between two masses is directly proportional to:
A. Product of the masses
B. Square of the distance between them
C. Difference of the masses
D. Sum of the masses

Correct Answer: Option A


Explanation:
Newton's law of gravitation: F = G·m₁m₂/r². Thus force is directly proportional to the product of the masses (m₁m₂) and inversely proportional to square of distance (r²). Option D incorrectly states 'directly proportional to square of distance' – it's inverse square. This fundamental law governs celestial mechanics. Memory tip: 'F ∝ m₁m₂ and F ∝ 1/r²'. Competitive exams often test precise wording of physical laws; distractors may reverse proportionality or misstate dependencies. Always recall the exact mathematical form.

This question belongs to: Science Physics
Question #3 Report Error
The root mean square speed of gas molecules is proportional to:
A. Square root of temperature
B. Square of temperature
C. Temperature
D. Inverse of temperature

Correct Answer: Option A


Explanation:
From kinetic theory, rms speed v_rms = √(3RT/M), where R is gas constant, T absolute temperature, M molar mass. Thus v_rms ∝ √T. This shows molecular speed increases with temperature but not linearly. Memory aid: 'Kinetic energy ∝ T; KE = ½mv² ⇒ v ∝ √T'. This conceptual question tests kinetic theory understanding, frequently examined in thermodynamics sections of competitive exams. Always use absolute temperature (Kelvin) in gas law calculations; Celsius would give incorrect proportionality.

This question belongs to: Science Physics