Spencer,+Dylan,+Jillian,+Nicole

=Lab: Elastic Potential Energy=
 * Lab Group:** Spencer, Dylan, Jillian, Nicole
 * Date:** 3/7/11


 * Objective:** What is the spring force constant? What is relationship between the velocity of the spring and the spring constant?


 * PART 1: FINDING THE SPRING FORCE CONSTANT **
 * Purpose:** To find the spring force constant of a given spring


 * Hypothesis:** By adding different masses to a spring, the change in the position will enable us to find the spring force constant (the slope of the graph).

**Materials:** - Spring - Stand - Hanging mass - Few masses (10g and 5g) **Procedure:**
 * 1) Set up apparatus and attach the mass hanger to the spring.
 * 2) Add first mass (5g) and record where it hangs with the ruler. (ruler is attached to the stand). This will be where the spring reaches equilibrium and will be used as 0 for all measurements.
 * 3) Add another mass (10g) to the apparatus and record the difference from this distance to the first.
 * 4) Repeat this step for masses 15g, 20g, 25g,30g and 35g.
 * 5) Create a graph on excel for the force vs. change in distance. Find the slope of the line. This becomes the spring force constant.


 * Data:**






 * PART 2: RELATIONSHIP BETWEEN SPRING FORCE CONSTANT AND VELOCITY **


 * Purpose:** To find the velocity based on the spring force constant


 * Hypothesis:** The farther the cart is pulled back, the less time it takes for the paper to go through the photogate. Therefore a faster velocity then at smaller distances.

- Spring - Cart and track - Photogate timer
 * Materials:**


 * Procedure:**
 * 1) Set up track and photogate timer. Attach a piece of paper to the cart and measure the width of the paper. Find the mass of the cart.
 * 2) Using the back of the cart, record the distance where the cart is on the track.
 * 3) Pull the cart to 40cm and start the photogate timer. Release the cart and record how long it takes. Do this three times with each distance and then change distances. (45cm, 50cm, 55cm,60cm).
 * 4) Record data into excel worksheet. Using the equation EPE=KE, find the velocity.
 * 5) Create a graph of velocity vs. distance and analyze.

media type="file" key="thread swing.mov" width="300" height="300"


 * Data:**




 * Sample Calculations:**

Percent Error:

1. Should all the k's be the same? Because all of the springs were supposedly the same, the k values should be the same or very similar. They could be slightly different due to how new the spring is/ how stretched out it is. Out k value was very similar to the class average, which proves theoretically they should be the same but each spring is not exactly the same, which is why they are very close.
 * Discussion:**

2. Discuss the graph v vs. x. What is the fit? Why did you choose this fit? Our graph has a direct linear relationship between the change in distance and the velocity. Both, our mass and our k value is constant. As the change in distance increases, the velocity of the spring increases as well.


 * Error Analysis and Conclusion:**

Through the completion of this experiment, we proved our hypothesis true. We can conclude that the further back the spring is pulled, the faster the velocity of the cart will be as it passes through the photo gate timer. Our percent error is pretty small but the reason that there is any at all could be because the position of the cart wasn't perfect, we didn't incorporate friction (very small source of error), and human error (the measurement of the distance the spring was pulled down could be off).