Circular Motion (H.C Verma)

JEE Advanced 2015 Discussion Forum › Mechanics questions › Circular Motion (H.C Verma)

Ques1) In the above figure, a smooth block loosely fits in a circular tube placed on a horizontal surface. The block moves in an uniform circular motion along the tube. Which wall (inner or outer) will exert a non zero normal contact force on the block?

Ques2) Consider the circular Motion of the earth around athe sun. Which of the following statements as more appropiate?
(a) Gravitational attraction of the sun o the earth is equlas to the centripetal acc.
(b) Gravitational attraction of the sun on the earth is the centripetal force.

Ques3) A heavy mass m is hanging from a string in =lbm, without breaking it. When thiis same mass is set into oscillation , the string breaks. Explain.

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3 Answers

sanchit ·2009-08-28 19:03:34

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Asish Mahapatra ·2009-08-29 03:43:23

Q1. If you work in the inertial frame, there must be a force which will provide the centripetal acceleration towards the centre of the circle.

It cant be the inner wall's reaction because its reaction can only be outwards. On the other hand, the reaction of the outer wall will be towards the centre. So the outer wall will exert a non zero normal contact force on the block.

This can be better visualised if u imagine yourself sitting in a car that's taking a turn. The wall that is in the opposite direction of the turn exerts a force

Q2. (b) is more correct.

Q3. When there is oscillation the magnitude of the tension varies. When the block goes below its equilibrium position, the tension increases So, the string snaps