Rotational Motion Question 52

Question: A solid cylinder of mass M and radius R rolls without slipping down an inclined plane of length L and height h. What is the speed of its centre of mass when the cylinder reaches its bottom?

[AIPMT 2003]

Options:

A) 43gh

B) 4gh

C) 2gh

D) 34gh

Show Answer

Answer:

Correct Answer: A

Solution:

Potential energy of cylinder at the top will be converted into rotational kinetic energy and translational kinetic energy.

So, energy conservation gives.

Mgh=12Mv2+12Iω2

=12Mv2+12MR22v2R2

(Icylinder=MR22)

So, Mgh=12Mv2+14Mv2

or Mgh=34Mv2

or v2=43gh

or v=43gh

Note: In a collision of two bodies whether it is perfectly elastic or inelastic, linear momentum is always conserved but kinetic energy need not to be conserved.



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