(adsbygoogle = window.adsbygoogle || []).push({}); 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 = .5mv^{2}= 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?

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# Homework Help: Kinetic Energy - Force done by friction

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