Question

Suppose an object's initial velocity is 10 m/s and its final velocity is 4 m/s. Mass is constant.

What can best be concluded about the object based on the work-energy theorem?
O Work is positive, the environment did work on the object, and the energy of the system increases.
Work is positive, the object did work on the environment, and the energy of the system increases.
Work is negative, the object did work on the environment, and the energy of the system decreases.
Work is negative, the environment did work on the object, and the energy of the system decreases.
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Answer 1

The best conclusion that can be drawn from the work-energy theorem is that work is positive, the object did work on the environment, and the energy of the system decreases. This is because the work-energy theorem states that the net work done by all forces acting on an object equals the change in its kinetic energy1. In this case, the object’s initial velocity is 10 m/s and its final velocity is 4 m/s, so its kinetic energy decreases by 6 m2/s2. The work done by all forces on the object must be equal to this negative value, which means that the object did work on the environment to reduce its speed. Therefore, work is positive and energy of the system decreases.

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