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Kelli weighs 435 N, and she is sitting on a playground swing that hangs 0.36 m above the ground. Her mom 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? B) If Kelli moves through the lowest point at 2.0 m/s, how much work was done on the swing by friction?

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anniwuanyanwu1

Answer:A 3.57m/s

B Workdone= 246.44J

Explanation:Given: change in heigt= 1-0.36=0.64, mass=435/9.8= 44.4Kg

PE=mgh=44.4×9.8×0.64=278.4J

Let PE=KE=1/2mv2

278.4=44.4/2×v^2

278.4=22.2v^2

V^2=278.4/22.4

V^2=12.79

V=3.57m/s

B. Velocity at the bottom of the swing is 2m/s

KE=44.4×0.36×2=-31.96J

Workdone=PE+KE=278.4-31.96=246.44J

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