Question

The wheel of a car is rotating at the rate of 1200 revolutions per minute. On pressing the accelerator for 10 seconds, it starts rotating at 4500 revolutions per minute. The angular acceleration of the wheel is

• A. $30degrees/se{c}^2$
• B. $1880degrees/se{c}^2$
• C. $40degrees/se{c}^2$
• D. $1980degrees/se{c}^2$

Answer 1

The correct option is D $1980degrees/se{c}^2$

Angular acceleration (a) = rate of change of angular speed
$=\frac{2\pi (n_2-n_1)}{t}=\frac{2\pi \left(\frac{4500-1200}{60}\right)}{10}=\frac{2\pi \frac{3300}{60}}{10}\times \frac{360}{2\pi }\frac{degree}{se{c}^2}=1980degree/se{c}^2.$