IIT JEE , AIEEE Forum - Physics , Mechanics - Doubt in law of conservation of energy!!!!

srivathsan.v

A 2 kg sphere moving horizontally to the right with an initial velocity of 5 m/s strikes the lower end B of an 8kg rigid rod AB of length 1.2 m. the rod is suspended from a hinge at A and is initially at rest. The coefficient of restitution between the rod and the sphere is 0.8. In respect of this collision, which of the following statements is true?

A. The law of conservation of energy does not hold good.

B. The total KE of the system has increased on collision

C. The law of conservation of angular momentum does not hold good

D. The angular momentum of system has increased on collision.

The answer is given as A. But energy must always be conserved. Can anyone tell the reason?

Milo_Breakin_free

This must be due to friction at the hinge.........We dont know how much energy is dissipiated due to that...............

Also we see that the coefficient of restitution is lesser than 1..........

hellraiser431991

wel u cant apply conservation of energy bcoz the collision is inelastic....
the KE bfore n after the collsion is not same....

rathin_123

you cannot apply energy convertion.because this is not totaly elastic collition.so whole KE willnot conserved.

here rod and shear both do rotational motion so you can apply angular momentum convertion here.

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