A parent swings a 11.5 kg

child in a circle of radius

0.711 m, making 12 revolutions

in 27.4 s. How much force does

the parent exert on the child?

(Unit = N)

22.5 N

Explanation:

Taking towards the center to be + x, sum of forces on the child in the x direction:

∑F = ma

F = m v² / r

F = m (ωr) ² / r

F = m ω² r

Plugging in values:

F = (11.5 kg) (12 rev * 2π rad/rev / 27.4 s) (0.711 m)

F = 22.5 N