Question

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
(c) a kite skillfully held stationary in the sky
(d) a car moving with a constant velocity of `30 kh//h` on a rough road
(e) a high speed electron in space free from all gravitational objects and free of electric and magnetic fields.

Answer 1

(a) As the drop of rain is failing with constant speed, in accordance with first law of motion, the net force on the drop of rain is zero .
(b) As the cork is floating on water, its weight is being balanced by the upthrust (equal to weight of water dissipated ) . Hence net force on the cork is zero.
(c ) Net force on a kite skilfully held stationary in sky is zero because it is at rest.
(d) Since car is moving with a constant velocity , the net force on the car is zero.
(e) Since electron is far away from all material agencies producing electromagnetic and gravitational forces, the net force on electron is zero.