1. Conservation of Energy
1/1/2019
Experiment 4
Conservation of Energy

2. Verify “KE + PE = Constant”
Experiment Goals
Verify “KE + PE = Constant”
Methods of Storing Potential Energy (Spring & gravitational potential)
Work-Kinetic Energy Theorem
Work = FDx = D(K.E.)
Determine Spring Constant

3. Part 1: Initial Setup
Measure mass of blue glider
Measure mass of Hanger + 2 Washers

4. Part 2 : Conservation of Energy in a System with Falling Weight
With Time, PE while KE 1m
However PE + KE = constant

5. Work-Kinetic Energy Theorem
For a constant applied force
Work = FDx [N-m or kg m/s2 - m]
K.E. = ½ mv2 [kg-m2/s2]
same units !
The tension in the string applies a constant force over some Dx.
Measure a and Dx with sonar … Work =MaDx
The change in the kinetic energy from the beginning to the end of that Dx should equal the Work
Measure vi and vf with sonar … DK.E.= ½ m(vf2-vi2)

6. Part 3(a): Determining Spring Constant
Plot “W” vs “x”.
The slope will give Spring Constant “k”
X-intercept will give xeq

7. Part 3(b) : Conservation of Energy in a System with Stretched Spring
The Stored Potential Energy In Stretched Spring is converted into Kinetic Energy of Glider
Is energy conserved? Limits based on experiment?

8. Conservation of Energy
Summary
Conservation of Energy
Glider and Gravity & Glider and Spring
Is Energy conserved? What is E?
Does expected value fall in uncertainty range of your experimental measurements
What is the spring constant?