A spherical ball of mass \( 2 \, \text{kg} \) falls from a height of \( 10 \, \text{m} \) and is brought to rest after penetrating \( 10 \, \text{cm} \) into sand. The average force exerted by sand on the ball is ________ \( \text{N} \). (Take \( g = 10 \, \text{m/s}^2 \))