Question

A table tennis ball has a radius of 2 cm. There are 3 table tennis balls stacked on top of one another in a cylinder that has the same diameter as the table tennis balls. The table tennis balls reach the top and bottom of the cylinder. How much volume is left inside the cylinder when the container is full?

Answer 1

Volume left = 16π cm³ or 50.265 cm³

Explanation:

Let's first find the surface area of the tennis ball.

S.A = (4/3)πr³

Radius of a ball = 2 cm

Thus;

S.A = (4/3)π(2)³

S.A = 32π/3

Since there are 3 radius balls that will make the cylinder full, then;

Surface area of 3 balls = 3 × 32π/3 = 32π

Now, formula for volume of cylinder is;

V = πr²h

r = 2 cm

h = 4 × 3 = 12 (since diameter of tennis ball is 4 cm)

Thus;

V = π × 2² × 12

V = 48π

Thus;

Volume left = Volume of cylinder - surface area of 3 balls = 48π - 32π = 16π cm³ or 50.265 cm³