Question

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

• A. 30 radians/sec²
• B. 1880 degrees/sec²
• C. 40 radians/sec²
• D. 1980 degrees/sec²

Answer 1

Answer: (D)

1980 degrees/sec²

Answer 2

Angular acceleration (α) = rate of change of angular speed

$= \frac{2\pi(n_{2} - n_{1})}{t} = \frac{2\pi\left( \frac{4500 - 1200}{60} \right)}{10}rad ⥂ / ⥂ sec^{2}$

$= \frac{2\pi\frac{3300}{60}}{10} \times \frac{360}{2\pi}\frac{degree}{sec^{2}} = 1980degree/sec^{2}$.