Question

If a wheel of diameter `28` inches moves at a speed of `100` kilometers per hour, how many radians per second does it revolve?

Answer 1

`78.12` radians per second

Explanation:

As diameter is `28`, circumference of the wheel is `28pi` inches or

`28pixx2.54=71.12pi` cm.

As it travels `100xx1000xx100` cm. in an hour,

wheel is taking `(100xx1000xx100)/(71.12pi)` revolutions in an hour or in `3600` seconds

i.e. `(100xx1000xx100)/(71.12pixx3600)` revolutions per second

or `(100xx1000xx100)/(71.12pixx3600)xx2pi` radians per second

i.e. `(100xx1000xx100)/(71.12xx1800)~=78.12` radians per second