1. The problem statement, all variables and given/known data Kelli weighs 435 N, and she is sitting on a playground swing seat that hangs 0.44 m above the ground. Tom pulls the swing back and releases it when the seat is 1.00 m above the ground. Assume that air resistance is negligible. (a) How fast is Kelli moving when the swing passes through its lowest position? SOLVED: 3.31 m/s (b) If Kelli moves through the lowest point at 2.0 m/s, how much work was done on the swing by friction? SOLVED: 154.284 Joules V at bottom in closed system = 3.31 m/s V at bottom in open system = 2.0 m/s Kelli's mass = 44.388 kg K in closed system = 243.158 Joules 2. Relevant equations K = .5mv2 = J(oules) W = Fd = J(oules) 3. The attempt at a solution I attempted to use the difference of the two velocities to find the kinetic energy in Joules, and it did NOT work. Any suggestions?