IC9.2_EVAC_System - problem Write out your equation Note...

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3/200 Emergency evac system – the cage and occupants has a mass of 320 kg and approaches the netting at a speed of 28 m/s. There is 20m of chain with a mass of 18kg/m attached to the netting, and the coefficient of friction between the chain and ground is 0.70. What is the time to bring the cage to a stop? Can you describe what is going on physically in terms of momentum. The cage and occupants have a linear momentum as it comes down the cable. It imparts an impulse to the netting and chain that is equal and opposite the impulse of the netting and chain on the cage. So some of the momentum of the cage will be “transferred” to the combined momentum of the cage/netting/chain. Then the chain friction will exert an impulse to the system that slows its momentum down over time. Can we use conservation of linear momentum for the first part of the
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Unformatted text preview: problem? Write out your equation. Note: Some books use L for linear momentum.-0.7(360*9.81) t = 0 – (320+360) (13.18) 2 3 3 v m v m dt F t m m m-= ∫ 2 Let call the velocity right after impact v 2 , and the velocity after it stops v 3. Now what equation do I use? Solve it! Solution: Problem Type: Find: Given: m cage = 320 kg, v1=28 m/s, m chain =360 kg, μ=0.7 Time t, to stop the cage Has initial speed and then an impulse of friction force. Try impulse momentum IC9.2 Emergency Evacuation Device 2 2 1 ) ( v m m v m v m G G chain cage chain chain cage cage + = + = Solve Reflection: Seems like a reasonable time for slowing down although I am not sure I would want to rely on chain friction? What if it is cold and icy and μ was much smaller?...
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This note was uploaded on 01/22/2011 for the course ME 212 taught by Professor Staff during the Spring '05 term at Cal Poly.

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