Title: Energy Lab
Partner: Kelly Schneck
Author: Saige Miller
Date: 12-23-15
Partner: Kelly Schneck
Author: Saige Miller
Date: 12-23-15
Purpose
The purpose of the lab is to prove the Law of Conservation of Energy.
Theory
Part One:
In the first part of the lab, we calculated the spring constant using Hook's Law, which states that for small deformations of an object the displacement is directly proportional to the deforming force. Once the force is removed, the object returns to its original shape. The equation below shows that the force (F) is equal to the spring constant (K) times the compression (X). |
Part Two:
For the second part of the lab, we compared our predicted velocity to the average velocity we collected using PhotoGate sensors. To do this, we had to derive an equation for velocity. |
Before the compressed spring is released, the cart has Elastic Energy. Once released the spring gives the cart Kinetic Energy.
Using the Law of Conservation of Energy, which states that energy cannot be created nor destroyed, it can only be transferred from one form to another, we derived an equation to find velocity. |
Experimental Technique
Part One:
In the first part of the lab, we set up a leveled plane with a cart and a spring. A string was placed on the cart and weight was hung on the other side of the string over a pulley. The weight was increased until the spring was compressed. Then, we divided the total weight used to compress the spring by 10. Each increment of weight was placed one at a time and the position of the cart was measured. Here we found the compression and spring constant. Part Two: For the second part of the lab, we used PhotoGate sensors to measure velocity. A "picket fence" with a flag length of 0.025m was used for the PhotoGate sensor. Weight was added to the cart for each trial. After 10 trails, we took the average velocity and compared that to the velocity we calculated. |
|
Data
Part One: The following data was used to find compression (X) and spring constant (K).
|
Part Two: We used a PhotoGate sensor to measure velocity with varying masses. Each mass listed was added to the original mass of the cart (0.548 kg). The flag length was 0.025m.
|
Analysis
Conclusion
The first part of the lab was to find the spring constant of the blue spring. I made a table relating the position and compression or force, then made a graph showing the relationship between the two. Since F=kx is a linear equation, the graph was linear. The spring constant was the slope of the line, 6.95 N/m.
The second part of the lab was to measure velocity. The blue spring was released from its compressed position to its relaxed position. As the diagram for this lab shows, the elastic energy was transferred to kinetic energy once the spring was released. The measured average velocity was 0.69 m/s, calculated velocity 0.74 m/s, with a percent error of 7.0%.
Reasons for error may include variation in the way the string was pulled to release the spring for each trial. Also, the PhotoGate may be slightly inaccurate when measuring the velocity.
The second part of the lab was to measure velocity. The blue spring was released from its compressed position to its relaxed position. As the diagram for this lab shows, the elastic energy was transferred to kinetic energy once the spring was released. The measured average velocity was 0.69 m/s, calculated velocity 0.74 m/s, with a percent error of 7.0%.
Reasons for error may include variation in the way the string was pulled to release the spring for each trial. Also, the PhotoGate may be slightly inaccurate when measuring the velocity.
Reference
Hooke's Law. (n.d.). Retrieved December 18, 2015, from http://www.britannica.com/EBchecked/topic/271336/Hookes-law
Giancoli, D. (1998). Physics: Principles with Applications (5th ed.). Upper Saddle River, N.J.: Prentice Hall.
Lahs Physics (n.d.). Retrieved December 18, 2015, from www.lahsphysics.weebly.com
Giancoli, D. (1998). Physics: Principles with Applications (5th ed.). Upper Saddle River, N.J.: Prentice Hall.
Lahs Physics (n.d.). Retrieved December 18, 2015, from www.lahsphysics.weebly.com