NEET Physics Question - Work Energy and Power - Work Done by Constant and Variable Forces

Assertion (A): A man carrying a load on his head and walking with uniform velocity on a street does not work against gravity.

Reason (R): When a body moves with uniform velocity, work done by all forces on this body is zero.

(1) Both (A) & (R) are true and the (R) is the correct explanation of the (A)

(2) Both (A) & (R) are true but the (R) is not the correct explanation of the (A)

(3) (A) is true but (R) is false

(4) Both (A) and (R) are false

Solution:

Assertion (A) is true because the displacement (horizontal) is perpendicular to the gravitational force (vertical), so work done \(W = \vec{F} \cdot \vec{d} = Fd \cos(90^{circ}) = 0\).

Reason (R) is also true by the Work-Energy Theorem for uniform velocity. However, (R) does not explain (A).

Rankers Physics

Work Done Against Gravity with Uniform Velocity

Solution:

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