A boy is riding a merry-go-round with a radius of . What is the centripetal force on the boy if his velocity is ?

A ball of mass on a string is rotating about the center axis with a velocity . If the tension force in the string is , what is the radius of the circular path of the ball?

A yo-yo trick called Around the World involves swinging the yo-yo around in a vertical circle at the end of its string. A man performs this trick with a yo-yo traveling at . If the length of the full string is , what is the centripetal force on the yo-yo?