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

$\begin {array} {1 1} (a)\;30\;rad/s^2 & \quad (b)\;1880\;deg/s^2 \\ (c)\;40\;rad/s^2 & \quad (d)\;1980\;deg/s^2 \end {array}$

$w =w_0 + \alpha t$
$\alpha =\large\frac{w-w_0}{t}$
$\qquad= \large\frac{\Large\frac{4500}{60}-\Large\frac{1200}{60}}{10}$
$\qquad= \large\frac{75-20}{10}$
$\qquad=\large\frac{55}{10}$
$\qquad= 5.5\;rev/s^2$
$\qquad= 36 \times 55 = 1980 \;deg /s^2$
edited May 26, 2014