- #1

zak100

- 462

- 11

## Homework Statement

Three identical balls fit snugly into a cylindrical can: the radius of spheres equals the radius of can, and the balls just touch the bottom and the top of the can,

If the formula for the volume of a sphere is

V = 4/3 PI * radius * radius * radius, what fraction of the volume of the can is taken up by the balls?

## Homework Equations

Volume of sphere = 4/3 PI * r * r * r

Volume of cylinder = PI * r * r * h

## The Attempt at a Solution

Suppose diameter of each ball is 2 so r = 1.

Vol of 3 balls = 3 * 4/3 PI * r * r *r = 4 * PI

Volume of cylinder = PI * r * r * h

Note h = 6 because 3 balls can fit in the cylinder

Volume of cylinder = 6 * PI

volume take up by balls is= 6* PI - 4 * PI = 2 PI

book is not doing subtraction.,

Some body please guide me why are we not doing subtraction.

Zulfi.