# lab3 - LAB 3 Work and Energy INTRODUCTION In this lab we...

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LAB 3: Work and Energy INTRODUCTION: In this lab, we will study the relationship between potential energy, kinetic energy, and work. This lab has three parts. In each part, we will find the work done on an object, by measuring how force and position vary over time. In part one, we will lift an object straight up into the air at a constant speed. In part two, we will stretch a spring. In part three, we will push a cart on a track in order to make it accelerate. These three mini- experiments will show us how work is related to energy. THEORY: Our experiment is based on the relationship between energy and work. Work is measure of energy transfer. Work is found by the equation W = F d, where work is the dot product of force and distance. There are two main kinds of energy used in this experiment: kinetic and potential energy. Kinetic energy equals 1/2mv 2 and potential energy equals mg h. These equations for energy come from E = mc 2 in some way. The work-energy theorem states that W = PE + KE. From this general equation for work and energy, we can find the work done by gravity or a spring. Wg = Fg* d = mg d. This equation is identical to the equation for gravitational potential energy: Ug = mg h. By their equations, gravitational potential energy equals the work done by gravity. For springs, Hooke’s Law says that F = k x, where k is the spring constant and x is the distance the string is compressed. Hooke’s Law is only valid for when force is constant, however. From this equation, we can find the value of the spring constant. Also, we can use this equation to find the equation for the work done by a spring. Work is the area under the force curve; work is the integral of force. The antiderivative of Hooke’s law gives Ws = ½ kx 2 . This is equivalent to elastic potential energy, because it measures the amount of potential energy stored in the spring. HYPOTHESIS: I think that in part 1, for an object being lifted at a constant speed, force will be constant. In part 2, a spring will have force that varies over time. In part 3, force will be constant for something that has an initial velocity. PROCEDURE:

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## This note was uploaded on 04/28/2008 for the course PHYSICS 11 taught by Professor Rogertobin during the Spring '06 term at Tufts.

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lab3 - LAB 3 Work and Energy INTRODUCTION In this lab we...

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