## College Physics (4th Edition)

The magnitude of the torque about the axis due to the child is $~784~N\cdot m$
The torque is $\tau = r\times F$, where $r$ is the smallest distance between the force vector and the rotation axis, and $F$ is the perpendicular component of the force vector. We can find the magnitude of the torque: $\tau = r\times F$ $\tau = r\times mg$ $\tau = (2.0~m)(40.0~kg)(9.80~m/s^2)$ $\tau = 784~N\cdot m$ The magnitude of the torque about the axis due to the child is $~784~N\cdot m$