A sphere of mass  and radius  is dropped in a liquid, then terminal velocity of sphere is proportional to
a)		b)		c)		d)

(c)

If a sphere of mass M and radius R is dropped in a liquid, its weight  acts vertically downwards. While upthrust  and viscous force  acts vertically upwards. Initially the body will be accelerated down. At a certain instant when viscous force F  will balance the net downward force, acceleration will become zero and the body will fall with constant velocity.