A body starts from rest on a long inclined plane of slope 45°. The coefficient of friction between the body and the plane varies as μ = 0.3x, where x is distance travelled down the plane. The body will have maximum speed (for g = 10 m/s ²) when x = (a) 9.8 m (b) 27 m (c) 12 m (d) 3.33 m

Answer: (d). Speed is maximum when acceleration becomes zero: gsin θ = μ gcos θ. μ = tan 45° = 1 0.3x = 1 ⇒ x = 10/3 ≈ 3.33 m So the answer is (d) 3.33 m.

A body starts from rest on a long inclined plane of slope 45°. The… | JEE Main 2013 (22 Apr, Shift 1)

Q29JEE Main 2013 · 22 APR · SHIFT 1Difficult

Friction on an Incline

A body starts from rest on a long inclined plane of slope 45°. The coefficient of friction between the body and the plane varies as $\mu = 0.3x$ , where x is distance travelled down the plane. The body will have maximum speed (for $g = 10$ m/s ${}^{2}$ ) when $x$ =

Show answer and solution

Answer: (d)

Speed is maximum when acceleration becomes zero: $g\sin\theta = \mu g\cos\theta$ .
$\mu = \tan 45^\circ = 1$
$0.3x = 1 \Rightarrow x = \frac{10}{3} \approx 3.33$ m
So the answer is (d) 3.33 m.

Report a mistake

Friction on an Incline question from JEE Main 2013 (22 Apr, Shift 1)

More questions on Friction on an Incline