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StepsDirectionsSet up a pulley system with 2 masses as shown below. The point of this "machine" is to lift mass B, so object A should have more mass than B. Release the masses from rest at the "start" position and time how long it takes for them to reach the "finish" position. Experiment with masses to find some that behave well before you do your calculations. They need to move slowly enough so that you can measure the fall time with precision. Collect whatever data are necessary in order to fill in the tables below. Do not try to write in the blacked-out cells. Do feel free to use formulas in the cells to calculate your answers. That's what I will be doing.
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Enter only numbers or formulas into the cells. NO units, punctuation, etc.
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1Record masses; convert to Kg.Mass (kg)
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Object A
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Object B
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2Collect height and time data. Use kinematics to find speeds, assuming constant acceleration. Perform energy calculations with energy formulasStarting Point/End Point Analysis, from an Energy Standpointtime (s)Height Above Surface (m)actual speed (m/s) -- **for end point, use speed just before contactKE (J)PE (J)Total Mechanical Energy (J)Total Energy (including "other energy")Other Energy -- e.g., thermal energy (J)
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Object AStarting Point00
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End Point ("finish")0
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Object BStarting Point00
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End Point ("finish")
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Total (this entire system)Starting Point
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End Point ("finish")
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3Perform various analyses (work, force of friction, and efficiency)Non-conservative work (work by friction)Work done by Non Conservative Forces (assume friction) -- (J)
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Force of friction Force of friction (assuming that the distance over which friction does work is the same as the distance traveled by the objects) -- (N)
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Overall EfficiencyCalculate the efficiency of this machine based on the assumption that the "output" is the total mechanical energy of the system just before block A hits the ground.
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Efficiency as an object acceleratorCalculate the efficiency of the machine based on the assumption that its sole purpose is to make object B reach the highest possible speed.
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4Calculate PowerPower in WattsPower in Horsepower
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Power: If this is a machine whose purpose is to give mechanical energy to object B, what is its power output? What is the rate at which it does this work?
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Power: If this is a machine whose purpose is to produce thermal energy, what is its power output?
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5Repeat the Friction Calculation using forces methods from earlier in the yearSystem acceleration (use kinematics)
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Force of friction (based on Fnet = ma)
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