If two objects with different masses have the same momentum, then their kinetic
ID: 1911369 • Letter: I
Question
If two objects with different masses have the same momentum, then their kinetic energies must be equal. In any isolated collision, both the momentum and kinetic energy of the entire system involved in the collision are conserved. The impulse imparted by the first object on the second object in a collision is equal to the impulse imparted by the second object on the first object in the same collision. If two objects collide and one is initially at rest, then it is possible for both to be at rest after the collision. Two blocks (mB = 3mA) collide as shown above. All surfaces are frictionless. If the initial speed of block A is 20 m/s and the final speed is 5 m/s, what is the final velocity of block B? If block A bounces back with the same speed it came in with, what must be true about the mass of block B?Explanation / Answer
By conservation of energy 1/2 mUa^2 = 1/2mVa^2 + 1/2MVb^2 m x 400 = m x 25 + 3m x Vb^2 Vb^2 = 125 Hence, Vb = 11.18 m/s If block B bounces back with the same speed it must imply that the mass of block B is very very large