Question

A wheel makes 12 revolutions per hour The radians it turns through in 20 minutes is:

• A. $8{\pi }^c$
• B. $16{\pi }^c$
• C. $24{\pi }^c$
• D. $32{\pi }^c$

Answer 1

The correct option is A $8{\pi }^c$

As the wheel makes $12$ revolutions per hour,
In $20$ minutes, it will make $12\times \frac{20}{60}=4$ revolutions.
In each revolution, the wheel covers ${360}^0$ or ${2\pi }^c$
So in $4$ revolutions, it will cover $4\times {2\pi }^c={8\pi }^c$