|Since the pivot point (the point about which the object
rotates) is at the centre of the merry-go-round, then the moment arm vector,
r, points from the centre to the rim of the merry-go-round. Using
the Right Hand Rule, we find that
the torque points into the screen.
Be careful with the moment arm vector. It is not the diameter of the merry-go-round, which was the given quantity, but the radius. So
= 70 N (into the screen)
Figure 1 Diagram from Question 2