Regarding a revolution based work physics problem. I don't know if I should take the 3 seconds into account when calculating distance (x). The problem says:
A 15 kg child is riding on a merry-go-round 2.2 m from its center and makes one revolution every 3 s. Friciton is the only force keeping the child from sliding, U= 0.35. How much work is done by friction in one revolution?