05-Oct-2016: Lab 11 Work Energy Theorem Activity

1. Title: Lab 11 Work Energy Theorem Activity
    Name: Qiwen Ye (Sherry)
    Lab partners names: Jae Yoo, Chandler
    Date: 05-Oct-2016

2. Purpose
This experiment is to measured the work done by a spring on a system by stretching a spring through a measured distance and make two graphs about position, force and kinetic energy in order to determine the relationship between work done and the kinetic energy.

3. Introduction
In theory, the work done by the spring should equal to the change in kinetic energy of the cart. We can measure the distance while we stretched the spring to get the work done.

4. Apparatus/Procedure
We set up the ramp, cart, motion detector, force probe, and spring as shown in the picture. Calibrated the force probe with a force of 4.9 N applied. The motion detector sees that the cart over the whole distance of interest - from the position where the spring is just unstretched to the position where it is stretched about 0.6 m.

In order to measure the work done, we used the LogPro to record the movement when the spring is stretched. Opened the experiment file called "Stretching Spring" to display the force vs. position. Then, zero the force probe and the motion detector with the spring supported loosely and unstretched. The motion detector was set to "reverse direction," so that toward the detector is the positive direction.

5. Measured Data
In the LogPro, we began graphing force vs. position as the cart is moved slowly towards the motion detector until the spring is stretched about 0.6 m. Then, we got the graph about force vs. position as shown. Then, we entered the formula KE=1/2mv^2 by using the velocity we got from the experiment and the mass of the cart in order to in order to get the graph of kinetic energy and position.

6. Explanation of Graph

The slope of the graph is the spring constant of the spring that we used, k=8.644 N/m. Because this graph is similar to the y=kx+b. The area of the graph force vs. position is the work done by the spring. Because:

Used the Analyze, Examine to find the change in kinetic energy of the cart after it is released from the initial position to several different final positions by using graph kinetic vs. position. We found that the work done by the spring is equal to its change in kinetic energy. Because the spring potential energy transform to the kinetic energy when we released the spring.

7. Conclusion

In this experiment, the work done by the spring is 0.6655 J; the kinetic energy is 0.556 J. The different percent is 16.4%. The friction between the cart and the track, the air resistance may cause the experiment has that differential. Overall, we determined that the work done of an object is equal to its the change in kinetic energy.