Question

An object of mass m moving at speed Vo strikes an object of mass 2m which had been at rest. The first object bounces backward along its initial path at speed Vo. Is this collision elastic, and if not, what is the change in kinetic energy of the system.

A) The collision is elastic
B) the kinetic energy decreases by mv^2
C) the kinetic energy increases by mv^2
the kinetic energy decreases by 1/2mv^2
D)

Answer 1

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A) The collision is elastic
B) the kinetic energy decreases by mv^2
C) the kinetic energy increases by mv^2
D)the kinetic energy decreases by 1/2mv^2

Answer 2

In any elastic collision
Kinetic energy b4 collision=kinetic energy after collision

Answer 3

Use conservation of momentum to figure out the velocity of the mass 2m

Then use @shamin s advice ;-)

Answer 4

the collision is elastic. in the study of elastic collisions in one dimension we have a special case where the light body collides against a massive body at rest, in which the light body rebounds with an equal and opposite velocity while the massive body practically remains at rest. imagine a light ball striking against a wall to understand it better. but this is a whole derivation, it's not at all theoretical.