Skip to content
dronacharya.ai
← JEE Main 2026 · 5 Apr · Shift 2
PhysicsSingle correct+4 / -1Question 28 of 75

JEE Main 2026 · 5 Apr · Shift 2, Physics question 28

A mass of 1 kg is kept on a inclined plane with 30° inclination with respect to horizontal plane and it is at rest initially. Then the whole assembly is moved up with constant velocity of 4 m/s. The work done by the frictional force in time 2 s is ________ J. (Take g=10g=10 m/s²)

Choose one option
Answer and worked solution

Official answer: A

Friction. The block stays at rest on the incline, so static friction balances gravity along it: f=mgsin⁡30∘=5f=mg\sin30^\circ=5 N, directed up the slope.

Displacement. The assembly moves vertically up by 4×2=84\times2=8 m. The friction force (along the incline) makes 60∘60^\circ with the vertical.

Work.
W=5×8×cos⁡60∘=20 J.W=5\times8\times\cos60^\circ=20\text{ J}.

(A)

Topics:Work by constant and variable forcesFriction
← Previous questionNext question →