Q.

Work done by a force on an object is zero, if

see full answer

Start JEE / NEET / Foundation preparation at rupees 99/day !!

21% of IItians & 23% of AIIMS delhi doctors are from Sri Chaitanya institute !!
An Intiative by Sri Chaitanya

a

the force is always perpendicular to its acceleration

b

the force is always perpendicular to its velocity

c

the object is stationary but the point of application of the force moves on the object

d

the object moves in such a way that the point of application of the force remains fixed.

answer is B, C, D.

(Unlock A.I Detailed Solution for FREE)

Ready to Test Your Skills?

Check your Performance Today with our Free Mock Test used by Toppers!

Take Free Test

Detailed Solution

Work done by a force on an object may not be zero if net acceleration is perpendicular to the force, hence (A) is not correct.

If displacement of the object is zero, then work done is zero, even if the point of application of the force is moving on it (Example, work done by friction on a block sliding on the floor is not zero, but work done by same friction on the floor is zero). Hence (B) is correct.

When a force is always perpendicular to velocity, work done is zero as π‘Š = ∫𝐹 . 𝑑𝑠̅ = 0, as instantaneous displacement is always perpendicular to the force. (Example, work done by centripetal force on an object moving in circular path is zero). Hence (C) is correct.

In pure rolling motion, work done by friction is zero. Though the body is moving, the point of application of friction is always at instantaneous rest. Hence (D) is correct.

Watch 3-min video & get full concept clarity

tricks from toppers of Infinity Learn

score_test_img

Get Expert Academic Guidance – Connect with a Counselor Today!

whats app icon