(a) A 15.0 kg child is riding a playground merry-go-round that is rotating at 35

Question

(a) A 15.0 kg child is riding a playground merry-go-round that is rotating at 35.0 rpm. What centripetal force must she exert to stay on if she is 1.50 m from its center?
  N
(b) What centripetal force does she need to stay on an amusement park merry-go-round that rotates at 3.00 rpm if she is 6.00 m from its center?
8.87 N
(c) Compare each force with her weight.
  (force from part (a) / weight)
  (force from part (b) / weight) .06

I have part B and C (B) correct but I cannot find A so therefore I cannot find C (B). Help!

Explanation / Answer

a) centripetal force =m w^2 * r

w = 35 x 2pi / 60 rad/s = 3.67 rad/s

F = 15 x 3.67^2 x 1.50 =302.25 N

b) w =3 x 2pi rad / 60 sec   = 0.314 rad/s

F =15x 0.314^2 x 6 = 8.88 N

c) Fa / weight = 302.25/ 15*9.81 = 2.05

Fb / weight = 8.88 / 15*9.81 = 0.0603

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