Question bank/JEE Main/Physics

JEE MainPhysicsModerateWork Power & Energy

A frictionless track ABCDE ends in a circular loop of radius R. A
body slides down the track from point A which is at height
h=82cmh = 82cm.
The maximum value of R for a body to complete the loop successfully is

Show answer and solution
Using energy conservation:
12mvB2=mgh\frac{1}{2}mv_{B}^{2} = mgh
VB=2mghmV_{B} = \sqrt{\frac{2mgh}{m}}
vB=2hg …(1)v_{B} = \sqrt{2hg}\ \ldots(1)
Also to complete vertical circle
vB=5gRv_{B} = \sqrt{5gR}...(2)
∴R=25h=32.8cm\therefore R = \frac{2}{5}h = 32.8cm

Source: Grass-G / P-06 Physics paper 14 October.docx

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