You throw a ball straight up. Compare the sign of the work done by gravity while the ball goes up with the sign of the work done by gravity while it goes down.

Question

Quizplus · Accepted Answer

Work done by gravity is equal to the force of gravity applied on the object multiplied by the displacement of the object. When the ball is thrown upwards, the force of gravity is acting downwards but the displacement is upwards, therefore the work done by gravity is negative. When the ball is coming back down, the force of gravity is acting downwards and the displacement is also downwards, therefore the work done by gravity is positive. Therefore, the sign of the work done by gravity is opposite in the two cases, making option C the correct choice.

You Throw a Ball Straight Up