A 23.0 kg child is riding a playground merry-go-round that is rotating at 30.0 rpm. What centripetal force, in N, must she exert to stay on if she is 2.00 m from its center

The value is  

Explanation:

From the question we are told that

   The mass of the child is  

   The angular velocity is  

   The distance from the center is  

Generally the centripetal force is mathematically represented as

=>      

=>    

diagram is missing, but i will try to explain your doubt.

answer:

amplitude is the maximum displacement or distance moved on a point of a vibrating body or wave measured from its equilibrium position.it is equal to half the length of vibration path.

the motion of a pendulum is a classic example of mechanical energy conservation. a pendulum consists of a mass (known as a bob ) attached by a string to a pivot point. as the pendulum moves it sweeps out a circular arc, moving back and forth in a periodic fashion.