Laws of Motion – Solutions

1) Give the magnitude and direction of the net force acting on:

(a) A drop of rain falling down with a constant speed

(b) A cork of mass 10 g floating on water

Solution:

a) As the rain drop is falling down with a constant speed, the net force on it is zero.

(a=0)

(b) The weight of a floating cork is balanced by the up thrust. Hence, the net force on it is zero.

2) Give the magnitude and direction of the net force acting on:

(c) A kite skillfully held stationary in the sky

(d) A car moving with a constant velocity of 30 km/h on a rough road.