A rubber ball of mass 10 gram and volume `15 cm^3` is dipped in water to a depth of 10m. Assuming density of water uniform throughtout the depth, find (a) the ac celeration of the ball, and (b) the time taken by it to reach the surface if it is relased from rest. `(Take g =980 cm//s^2)`

Answer

(a)`4.9 m//s^2` (b) 2/02 s

Explanation

(a) Effective upward thrust on the ball is `F = F_B - mg= ma` or `a = (1)/(m) [ F_B - mg]`
` = (1)/(10) [ (15xx1 xx 980) - 10 x 980]`
` =490 cm//s^2 = 4.9 m//s^2` (b) Time taken by ball to reach the surface of water is `t = sqrt((2h)/(a)) = sqrt((2xx10)/(4.9)) = 2.02s`