Laws of Motion

JEE Main level, single correct, medium

192 of 210

Question 192 of 210

A smooth block is released at rest on a 45∘45^{\circ} incline and then slides a distance d. The time taken to slide is n\mathrm{n} times as much to slide on rough incline than on a smooth incline. The coefficient of friction is

Show answer and solution

Answer: (A) μk=1−1n2\mu_{\mathrm{k}}=1-\frac{1}{\mathrm{n}^2}

d=12g2t12\mathrm{d}=\frac{1}{2} \frac{\mathrm{g}}{\sqrt{2}} \mathrm{t}_1^2
 d=12g2(1−μk)t22\mathrm{~d}=\frac{1}{2} \frac{\mathrm{g}}{\sqrt{2}}\left(1-\mu_{\mathrm{k}}\right) \mathrm{t}_2^2
t22t12=n2=11−μk\frac{\mathrm{t}_2^2}{\mathrm{t}_1^2}=\mathrm{n}^2=\frac{1}{1-\mu_{\mathrm{k}}}

JEE Main question paper PDF

Open a shift to read the full paper on this page, or download it.

JEE Main 2025 Apr 2 Shift 1 question paper

Open Download PDF

Opening paper…

Explain it as a whiteboard videoStep-by-step, in Hinglish or English. Your first video needs no login.Solved it on paper but got it wrong?Upload a photo of your working. Mistake Doctor marks the exact line that broke.
See it move: Laws of motion, friction and pulleys simulationDrag the sliders and watch the numbers in this question change.

More Physics practice

JEE Main Physics practice question on Laws of Motion (Frictional force), with the answer and a step-by-step solution. Scan a question from your own book or paper to get a whiteboard video.