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Tanero
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Homework Statement
A merry-go-round is sitting in a playground. It is free to rotate, but is currently stationary. You can model it as a uniform disk of mass 220 kg and radius 100 cm (consider the metal poles to have a negligible mass compared to the merry-go-round). The poles near the edge are 86 cm from the center.
Someone hits one of the poles with a 9 kg sledgehammer moving at 15 m/s in a direction tangent to the edge of the merry-go-round. The hammer is not moving after it hits the merry-go-round.
How much energy is lost in this collision? (enter a positive number for the absolute value in Joules)
Homework Equations
conservation of momentum
KE of rotation =.5mv2
KE of linear motion = .5Iω2
Lost of energy=KErot-KElinear
The Attempt at a Solution
I assume that hummer hit pole tangentially and collision was elastic.
My way of thinking is that energy transfer of KE of linear motion to KE of rotation. Thus I need to find KElinear and KErot. Where KElinear is easy to find.
To find KErot, first, apply conservation of momentum.
mhvh=mdvd
Linear momentum was transferred to rotational motion. Where vd is tangential velocity of disk. vd is velocity of hummer. Then, v=ωd (d-distance from center to metal pole)
From these, I can find ω and put it into my KErot
Than I can find my energy loss. Right?
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