Physics Circle home Student Login

Home›Chapters›Laws of Motion PYQs›Connected Bodies & Pulleys›Question 22

JEE Main 2022 (27 Jul, Shift 2) · Connected Bodies & Pulleys

Connected Bodies & Pulleys question from JEE Main 2022 (27 Jul, Shift 2)

Q22JEE Main 2022 · 27 JUL · SHIFT 2Medium

Connected Bodies & Pulleys

A block 'A' takes 2 s to slide down a frictionless incline of 30∘^\circ and length 'l', kept inside a lift going up with uniform velocity 'v'. If the incline is changed to 45∘^\circ, the time taken by the block, to slide down the incline, will be approximately:

Show answer and solution

Answer: (c)

  1. A lift moving with uniform velocity is an inertial frame, so effective gg is unchanged.
  2. On a frictionless incline: l=12gsin⁡θ t2⇒t∝1sin⁡θl = \frac{1}{2}g\sin\theta\, t^2 \Rightarrow t \propto \dfrac{1}{\sqrt{\sin\theta}}.
  3. t′=2sin⁡30∘sin⁡45∘=20.707=2×0.84t' = 2\sqrt{\dfrac{\sin 30^\circ}{\sin 45^\circ}} = 2\sqrt{0.707} = 2 \times 0.84
  4. t′≈1.68 st' \approx 1.68\text{ s}, so the answer is (c).
Report a mistake

More questions on Connected Bodies & Pulleys