A stone of mass 0.1 kg is thrown vertically upwards . Given the magnitude and direction of the net force on the stone (a) during its upward motion (b) during its downward motion (c)at the highest point , where it momentarily comes to rest .

A pebble of mass 0.05 kg is thrown vertically upwards. Give the direction and magnitude of the net force on the pebble, (a) during its upward motion, (b) during its downward motion, (c) at the highest point where it is momentarily at rest. Do your answers change if the pebble was thrown at an angle of 45^@ with the horizontal direction? Ignore air resistance.

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 helicopter of mass 1000 kg rises with vertical acceleration of 15 ms^(-1) . The crew and the passengers weigh 300 kg. Give the magnitude and direction of the a) force on the floor by the crew and passengers b) action of the rotor of the helicopter on the surrounding air c) force on the helicopter due to the surrounding air