A 1.0-kg object moving in a certain direction has a kinetic energy of 2.0 J.It hits a wall and comes back with half its original speed.What is the kinetic energy of this object at this point?
A)2.0 J
B)1.0 J
C)0.50 J
D)0.25 J
E)4.0 J

Question

Quizplus · Accepted Answer

The kinetic energy of an object is given by the equation KE = (1/2)mv^2, where m is the mass of the object and v is its speed. Initially, the object has a kinetic energy of 2.0 J. When it hits the wall and comes back with half its original speed, its new speed is (1/2)v. Using the equation for kinetic energy, we can find the new kinetic energy:

KE' = (1/2)m(1/2v)^2 = (1/8)mv^2 = (1/8)(2.0 J) = 0.25 J

Therefore, the kinetic energy of the object at this point is 0.50 J, or choice C.

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