Question

A boy throws a rubber ball vertically upwards .What type of work , positive or negative ,is done :+-

a)by the force applied by the boy.

b)by the gravitational force of earth..

Answer 1

Hey!

a. Positive work is done by the force applied by the boy because the ball continue to move in the direction of force.

b. Negative work is done by the gravitational force of earth because the ball moves in direction of force i.e opposite to gravitational force.

Hope It Helps You!

Answer 2

a)

• When the boy throws the ball vertically upwards the force applied by the boy is positive.

• When the force has a component in the same direction as the displacement of the object, the force is doing positive work.

b)

• When the boy throws the ball vertically upwards work done by the gravitational force of the earth is negative.

• When the force has a component in the direction opposite to the displacement, the force does negative work.