Wednesday, April 15, 2015

8-Apr-2015: Conservation of Energy - Mass-Spring System

Purpose:
     The purpose of this lab was to demonstrate that energy is conserved in a system of a spring with a hanging mass.

Materials:
-A spring
-Rods and clamps
-A 50 g mass hanger and an additional 200 g mass.
-Force sensor and motion detector

Short summary of lab:
     We know that work will consist of kinetic energy (KE), elastic potential energy (EPE), and gravitational potential energy (GPE). The changes on a hanging mass are easily calculated, however, the changes on the spring must be accounted for. Before setting up the lab, we derived what the KE and the GPE on the spring would be. After these derivations, we found the spring constant (K) and made calculated columns to graph the position, velocity, KE, EPE, GPE all vs time.

Process:
     We first derived the GPE and the KE of the spring.

     In short, the GPE = 0.5(Mspring)gy and KE = 0.5((1/3)Mspring)v^2

     We then obtained K by having the following setup

     We zero the motion detector with the spring and the mass hanger. We then pull on the 50 g mass hanger and obtain a Force vs Time and Stretch vs Time data. We find K by using the Force vs Stretch graph and obtaining the slope of the line. We found K = 8.427 N/m

     We obtain the position and velocity of the mass by using the motion detector. We then graph
Position vs time

Velocity vs time

KE vs time

GPE vs time

EPE vs time

Conclusion:

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