Physics
posted by Dave .
A child of mass 40.0 kg is swinging on a swing with ropes of length 4.0 m. How long does it take the child to swing from the maximum height on one side to the other?

Half of the period of the swing (which is essentially a pendulum).
It will be independent of the mass.
The period of a pendulum is
2 pi sqrt(L/g)
Half of that will be your answer.
Having two ropes instead of one does not change the formula from that of a simple pendulum. 
Thanks. I was confused by the way the question was worded and my answer was 2 times bigger than what the answer is supposed to be.