A child throws a rubber ball upward , then what type of work is done in two situations given below ? Positive or negative .
(a) Force given by a child .
(b) By gravitational force of the earth .

When is the work done by a force is positive and negative ?

When the earth revolves around the sun, the work done by the gravitational force of the sun is zero.

The work done by a gravitational force acting on a free fall body will be positive , negative or zero ?

A body is being raised to height h from the surface of earth. What is the sign of work done by (a) applied force and (b) gravitational force ?

The sign of work done by a force on a body is important to understand .State carefully if the following quantities are positive or negative : (a) work done by a man in lifting a bucket out of a well by means of a rope tied to the bucket . (b) work done by gravitational force in the above case , (c ) work done by friction on a body siding down an inclined plane , (d ) workdone by an applied force on a body moving on a rough horizontal plane woth uniform velocity . (d) work done by the resistive force of air on a vibrating pendulum in bringing it to rest .

A player throws a ball upwards with an initial speed of 29.4 ms^(-1) (a) What is the direction of acceleration during the upward motion of the ball ? (b) What are the velocity and acceleration of the ball at the highest point of its motion ? (c) Choose the x = 0 m and t=0 s to be the location and time of the ball at its highest point vertically downward direction to be the positive direction of x-axis and give the signs of position, velocity and acceleration of the ball during its upward and downward motion. (d) To what height does the ball rise and after how long does the ball return to the player's hands ? (Take g = 9.8 ms^(-2) and neglect air resistance).

A rain drop of radius 2 mm falls from a height of 500 m above the ground .It falls with decreasing acceleration (due to viscous resistance of the air) until at half its original height , it attains its maximum (terminal) speed, and moves with uniform speed thereafter .What is the work done by the gravitational force on the drop in the first and second half of its journey ?What is the work done by the resistive force in the entire journey if its speed on reaching the ground is 1 ms^(-1) ?

A rain drop of radius 2mm falls from a height of 500 m above the ground. It falls with decreasing acceleration (due to viscous resistance of the air) until at half its original height, it attains its maximum (terminal) speed, and moves with uniform speed thereafter. What is the work done by the gravitational force on the drop in the first and second half of its speed on reaching the ground is 10 ms^(-1) ?