Question

A ball of relative density 0.8 falls into water from a height of 2 m. The depth to which the ball will sink is (neglect viscous forces)
A. 8 m
B. 2 m
C. 6 m
D. 16 m

Answer 1

Correct Answer - A
Velocity of ball just before striking water surface, `v=sqrt(2gh)`
or `v=sqrt(4g) m s^(-1) " " (h=2m)`
or `a=(V rho_(w)g-Vrho g)/(V rho)=((1-0.8)/(0.8))g=g//4`
Now, depth to which ball will sink is
`d=(v^(2))/(2a)=(4g)/(2g//4)=8m`