Buoyancy: A hollow steel ball of diameter 3.0 m barely floats in water. What is the thickness of the wall of the ball? The density of iron is 7.87 g/cm³ and that of water is 1000 kg/m³. A) 6.6 cm B) 37 cm C) 131 cm D) 79 cm

Question

Quizplus · Accepted Answer

For the steel ball to barely float, its weight must equal the weight of the water it displaces. The volume of water displaced is equal to the volume of the ball, which can be calculated using the formula for the volume of a sphere ($V = \frac{4}{3}\pi r^3$). The thickness of the steel wall can be found by considering the volume of steel needed to have the same weight as the displaced water, taking into account the density of steel and water. Calculating this leads to a thickness that matches the value given in option A.

Buoyancy: a Hollow Steel Ball of Diameter 3