Question

A merry-go-round, which may be approximated as a solid disk of mass 90.0 kg and radius 2.00 m, is originally at rest but free to rotate in the horizontal plane about its center. A child applies an external force of 20.0 N tangentially to the outer edge of the merry-go-round, for a duration of 15.0 s.
(a) What is the final angular velocity of the merry-go-round?
(b) What is the average power supplied by the child in the process?
(c) After getting it going, the 45-kg child steps, with negligible velocity, on the outer edge of the merry-go-round. What is the new angular velocity of the child plus merry-go-round system?
(d) Is kinetic energy conserved in the process of part (c)? Justify your answer.

answers below but i need help with steps

(a) w 3.33 rad/s (b) P -66.7 W (c) 1.67 rad/s (d) No, AK 500 J, so kinetic energy is lost. The collision of the child with the merry-go-round is completely inelastic (the stick together), so kinetic energy cannot be conserved.

Answer 1

ny ey'.dk : 1 (박..:) 1악 づ u, ).CTAadl s Realen:-duet.tyi다,'on beli un rhe round Lyi