Henry Ernest Dudeney/Puzzles and Curious Problems/226 - The Circulating Motor-Car/Solution

by : $226$

 * The Circulating Motor-Car

Solution
Approximately $62.832$ feet.

Proof
As the outer wheels are going twice as fast as the inner wheels, they are travelling along a circle of twice the circumference.

The circumference is propportional to the radius.

It follows that the radius of the outer circle is twice $5$ feet, that is, $10$ feet.

From Perimeter of Circle that is $2 \times \pi \times 10$ which is approximately $62.832$ feet.