work/systems??

Question

Which of the following is true if work has been performed on a system?

a.) All objects are in the same place before and after the work is performed.
b.) No force is exerted on the system.
c.) An object in the system must have been moved against a force.

Answer 1

Work is done on an object if it moves in the direction of an applied force. An applied force must be used to move an object against a force, so c) is your answer.