25
QuizMultiple Choice

Unit Test — Unit test

Question 25 • NC-Physical Science CR 2024

Pablo prepares to lift a barbell. During which stage of the lift does Pablo do work on the barbell?

Answer
A
when he holds the barbell up above his head
B
when he applies force to the barbell but has not moved it
C
when he lifts the barbell from the floor to his chest
D
when he lets go of the barbell and allows it fall to the ground

Explanation

Work is done when a force causes an object to move in the direction of that force. Pablo applies an upward force and moves the barbell upward as he lifts it from the floor to his chest, so he does work during that stage. Holding it still or pushing without moving it does not do work on the barbell.

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