Mechanics > Work and Energy > Conservation of Energy

DCS# 1M40.xx

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ENERGY ANALOGY

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APPARATUS

spring scale and pail	101-05-G5
several golf balls	202-01-F6
beaker	101-05-C
opaque liquid, e.g. milk	IGA

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DESCRIPTION

This is based on the energy analogy from the Feynman lectures.  The golf balls represent energy.  Some balls are placed in the pail and others in the beaker of milk.  Although they are hidden from sight, the number of balls can be determined from the change in the spring scale reading and the change in volume of the beaker contents.  You can write a formula for the number of hidden balls in the system in terms of measurable quantities:  n = ΔV/V_ball + ΔW/W_ball.  If no balls are added to or removed from the system, the result of that formula will remain constant even if balls are transferred between the pail and the beaker.