Question 592: Centre of Mass and Rotational Motion

Question

A disc of radius 0.4 metre and mass 1 kg rotates about an axis passing through its centre and perpendicular to its plane. The angular acceleration is 10 rad s$$^{-2}$$. The tangential force applied to the rim of the disc is

Accepted Answer

$$\mathrm{R}=0.4 \mathrm{~m}, \mathrm{M}=1 \mathrm{~kg}, \alpha=10 \mathrm{~rad} / \mathrm{s}^2$$
$$I=\frac{M^2}{2}=\frac{1 	imes(0.4)^2}{2}=0.08 \mathrm{~kg} \mathrm{~m}^2$$
Torque, $$	au=\mathrm{I} \alpha=0.08 	imes 10=0.8 \mathrm{~N}-\mathrm{m}$$
Also, $$	au=F R$$
or $$F=\frac{	au}{R}=\frac{0.8}{0.4} \quad=2 \mathrm{~N}$$

Answer

2N

Answer

3N

Answer

4N

Answer

5N

Centre of Mass and Rotational Motion

A disc of radius 0.4 metre and mass 1 kg rotates about an axis passing through its centre and perpendicular to its plane. The angular acceleration is 10 rad s$^{-2}$. The tangential force applied to the rim of the disc is

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