Question

Answer these questions on the basis of given figure and information
A cord of negligible mass is wound round the rim of a fly wheel (disc) of mass 20 kg and radius 20 cm. A steady pull of $25N$ is applied on the cord as shown in figure. The flywheel is mounted on a horizontal axle with frictionless bearings

Compute the angular acceleration of the wheel

• A. $12.50s^{-2}$
• B. $6s^{-2}$
• C. $10s^{-2}$
• D. $8s^{-2}$

Answer 1

Answer: (A)

We use, $I\alpha =\tau$
The torque, $\tau =FR$
$=25\times 0.20N-m(\text{ as }R=0.20m)$
$=5.0N-m$
$I=MOI$ of flywheel about its axis
$=\frac{M{R}^2}{2}=\frac{20.0\times (0.2{)}^2}{2}$
$=0.4kg-m^2$
$\alpha =$ angular acceleration
$=5.0N-m/0.4kg-m^2=12.50s^{-2}$