Question

You and your friends are playing in the swimming pool with a 25-in diameter beach ball. How much force (in Newtons) would be needed to push the ball completely under water?

Answer 1

Given:

$d=\rm 25\: in=0.635\: m$

$\rho=\rm 1000\: kg/m^3$

$g=\rm 9.8\:\rm N/kg$

The buoyant force

$$F=g\rho V, \quad V=\frac{4}{3}\pi R^3$$

Hence

$$F=\rm 9.8*1000*4/3*3.14*(0.635/2)^3=1313\: N$$