# physics

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A 52kg teen grabs onto a rope swing. The length of rope between the teen and the pivot point above is 4.5m, and the rope makes an angle of 40o relative to vertical. Calculate his change in potential energy as he swings down and out to the point where the rope is in the vertical position.

• physics -

Δh=L-Lcosα=L(1-cosα)
ΔPE=mg Δh=mgL(1-cosα)=
=52•9.8•4.5•(1-cos40°) = …

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