Medium MCQ +4 / -1 PYQ · JEE Mains 2025

A uniform solid cylinder of mass ' m ' and radius ' r ' rolls along an inclined rough plane of inclination $45^{\circ}$. If it starts to roll from rest from the top of the plane then the linear acceleration of the cylinder's axis will be

  1. A $\sqrt{2} \mathrm{~g}$
  2. B $\frac{1}{\sqrt{2}} \mathrm{~g}$
  3. C $\frac{1}{3 \sqrt{2}} \mathrm{~g}$
  4. D $\frac{\sqrt{2} g}{3}$ Correct answer

Solution

<p>The acceleration of the center of mass for a rolling object down an incline is given by:</p> <p>$a = \frac{g \sin\theta}{1 + \frac{I}{m r^2}}$</p> <p>For a uniform solid cylinder, the moment of inertia about its central axis is:</p> <p>$I = \frac{1}{2} m r^2$</p> <p>Substituting this into the expression for acceleration:</p> <p>$$ a = \frac{g \sin\theta}{1 + \frac{\frac{1}{2} m r^2}{m r^2}} = \frac{g \sin\theta}{1 + \frac{1}{2}} = \frac{g \sin\theta}{\frac{3}{2}} = \frac{2}{3} g \sin\theta $$</p> <p>For an incline of $45^\circ$, we have:</p> <p>$\sin 45^\circ = \frac{\sqrt{2}}{2}$</p> <p>Thus, the acceleration becomes:</p> <p>$a = \frac{2}{3} g \cdot \frac{\sqrt{2}}{2} = \frac{\sqrt{2} g}{3}$</p> <p>Therefore, the linear acceleration of the cylinder's axis is:</p> <p>$\frac{\sqrt{2} g}{3}$</p>

About this question

Subject: Physics · Chapter: Rotational Motion · Topic: Centre of Mass

This question is part of PrepWiser's free JEE Main question bank. 158 more solved questions on Rotational Motion are available — start with the harder ones if your accuracy is >70%.

Drill 25 more like these. Every day. Free.

PrepWiser turns these solved questions into a daily practice loop. Chapter-wise drills, full mocks, AI doubt chat. No auto-renew.

Start free →