JEE Main · 2026 · 23 Jan 2026 · Shift 2 · Kinematics

A block is sliding down on an inclined plane of slope

θ

and at an instant

t = 0

this block is given an upward momentum so that it starts moving up on the inclined surface with velocity

u

. The distance

(S)

travelled by the block before its velocity become zero, is ____.
(g = gravitational acceleration)

Answer: (A)

Solution

Before

t = 0

the block slides down at constant velocity, so kinetic friction balances the gravity component:

μ m g cos θ = m g sin θ

, giving

μ = tan θ

. When it is projected up with speed

u

, both gravity and friction act down the incline, so the retardation is

a = g sin θ + μg cos θ = g sin θ + g sin θ = 2 g sin θ

. The distance until it stops is

S = \frac{u ^{2}}{2 a} = \frac{u ^{2}}{4 g sin θ}

JEE Main · 2026 · 23 Jan 2026 · Shift 2 · Single correct option