Calculate the change in the total kinetic energy of the system that occurs during the following collision.  On a frictionless horizontal air table, puck A (with mass 0.252 kg) is moving toward...

Calculate the change in the total kinetic energy of the system that occurs during the following collision. 

On a frictionless horizontal air table, puck A (with mass 0.252 kg) is moving toward puck B (with mass 0.368 kg), which is initially at rest. After the collision, puck A has velocity 0.125 m/s to the left, and puck B has velocity 0.646 m/s to the right.

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justaguide | College Teacher | (Level 2) Distinguished Educator

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Energy is a scalar quantity. And the total momentum is conserved in a collision.

In the problem, initially puck A (with mass 0.252 kg) is moving toward puck B (with mass 0.368 kg), which is initially at rest on a frictionless horizontal air table. After the collision, puck A has velocity 0.125 m/s to the left, and puck B has velocity 0.646 m/s to the right.

The total momentum before collision is 0.252*v + 0 and after the collision it is equal to 0.252*0.125 - 0.368*0.646 = -0.206228

0.252*v = -0.206228

=> v = 0.8183 m/s

The initial velocity of puck A was 0.8183 m/s

The initial kinetic energy of the system initially was 0.252*0.8183^2 = 0.1687 J

After collision the kinetic energy in the system is 0.252*0.125^2 + 0.368*0.646^2

=> 0.1575 J

The change in the total kinetic energy of the system is 0.01127 J.

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