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Elastic collision of general masses

Student 3057 9 years ago updated by Physics Tutorial Center Staff 9 years ago 1

A ball of mass m makes a head-on elastic collision with a second ball that's at rest. The first ball rebounds with a speed equal to .6 of its original speed. What is the mass of the second ball?

Can't the mass be anything and will just have a different velocity accordingly?

Answer

Answer
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The reason there is a definite mass of the second ball is that the collision is elastic, meaning that energy is also conserved in addition to momentum. Now we have two equations,


p_initial = p_final

KE_initial = KE_final


and two unknowns (the masses), so we will be able to solve for the second ball's mass.

Answer
Closed

The reason there is a definite mass of the second ball is that the collision is elastic, meaning that energy is also conserved in addition to momentum. Now we have two equations,


p_initial = p_final

KE_initial = KE_final


and two unknowns (the masses), so we will be able to solve for the second ball's mass.