Question

The 16 cm. diameter disk in the figure can rotate on an axle through its center.

What is the net torque about the axle? τ=________N*m
Express your answer using two significant figures. Assume the counterclockwise rotation as positive.

Answer 1

Sign convention:

Clockwise torque: negative

Anticlockwise torque: positive Radius of the disk, \(\mathrm{r}=16 / 2=8 \mathrm{~cm}=0.08 \mathrm{~m}\)

Torque \(=\) force \(^{*}\) perpendicular distance

$$ \begin{aligned} \text { Net torque } &=20 * 0.05+20 * 0+30 \sin 45 * 0.05-30 * 0.08 \\ &=1+0+1.06-2.4 \\ &=-0.34 \mathrm{Nm} \\ &=0.34 \mathrm{Nm} \text { (clockwise) } \end{aligned} $$

Answer 2

Tnhssifsma -(6.00)(-30%Mwa (0.05)(20)Sha1oN 106N 2-2.4+1+1-06+0 034 N CClerkwt diehn)