math
posted by R .
The period T (time in seconds for one complete cycle) of a simple pendulum is related to the length L (in feet) of the pendulum by the formula 8T^2=Pi^2L. If a child is on a swing with a 10foot chain, then how long does it take to complete one cycle of the swing?

8T^2 = (3.14)^2*L
Substitute 10 for L and solve for T.
8T^2 = (3.14)^2 *10
Divide both sides of Eq. by 8.
T^2 = (3.14)^2*10/8 = 12.34.
Take sqrt of both sides:
T = 3.51 seconds.