Question 596: Centre of Mass and Rotational Motion

Question

A disc of radius 0.4 m and mass one kg rotates about an axis passing through its centre and perpendicular to its plane. The angular acceleration of the disc is 10 rad/s$$^2$$. The tangential force applied to the rim of the disc is

Accepted Answer

$$\mathrm{R}=0.4 \mathrm{~m}, \mathrm{M}=1 \mathrm{~kg}, \alpha=10 ~\mathrm{rad} / \mathrm{s}^2$$
Moment of inertia $$\mathrm{I = {{M{R^2}} \over 2} = {{1 	imes {{(0.4)}^2}} \over 2} = {{0.16} \over 2} = 0.08}$$ kg m$$^2$$
Torque
$$\begin{aligned}
& 	au=\mathrm{RF}=\mathrm{I} \alpha \
& 	herefore \mathrm{F}=\frac{\mathrm{I} \alpha}{\mathrm{R}}=\frac{0.08 	imes 10}{0.4}=2 \mathrm{~N}
\end{aligned}$$

Answer

4 N

Answer

1 N

Answer

2 N

Answer

8 N

Centre of Mass and Rotational Motion

A disc of radius 0.4 m and mass one kg rotates about an axis passing through its centre and perpendicular to its plane. The angular acceleration of the disc is 10 rad/s$^2$. The tangential force applied to the rim of the disc is

Choose the correct answer: