A 4.00 kg object is moving at 5.00 m/s NORTH.It strikes a 6.00 kg object that is moving WEST at 2.00 m/s.The objects have a completely inelastic (stick together)collision.The kinetic energy lost in the collision is
A) 34.8 J.
B) 28.7 J.
C) 20.4 J.
D) 18.7 J.
E) 14.9 J.

Question

Quizplus · Accepted Answer

The initial kinetic energy is the sum of the kinetic energies of both objects: (1/2)(4 kg)(5 m/s)^2 + (1/2)(6 kg)(2 m/s)^2 = 50 J + 12 J = 62 J. After the collision, the combined mass is 10 kg and the velocity can be found using conservation of momentum. The final kinetic energy is (1/2)(10 kg)(2.2 m/s)^2 = 27.2 J. The kinetic energy lost is 62 J - 27.2 J = 34.8 J.

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