Lab: Kinetic Energy — Unit test

Question 6 • WA-Physical Science B

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?

Answer

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.

Explanation

By the work-energy theorem, the net work on the object equals its change in kinetic energy. Its speed drops from 10 m/s to 4 m/s, so its kinetic energy decreases and the work on it is negative. Energy is transferred from the object to the environment, so the object does work on the environment and the system’s energy decreases. This matches choice C.

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