Lab#11: Kinetic Energy and the Work-Kinetic Principle

Kinetic Energy & Work-Kinetic Principle

Samuel
Ellis
Mia
10-5-2016

Purpose:

To measure the work done as we stretch cart with spring acting on opposite direction.

Theory:

We all know the formula work equal to force times distance and the law of conservation of energy. By assuming there's no friction, the energy will equal to each other. Furthermore, when a cart is moving on a surface with a spring attach on the opposite direction, the kinetic energy will equal to spring potential energy. Then we can determine the force acting on the spring and its velocity.

Procedure:

EXPT 1.
1. Calibrate the force prob with a force of 4.9 N applied.
2. Set up the ramp, cart, motion detector, force prob, and spring.
3. Use cart stopper at the end of ramp
4. Be sure the motion detector sees the cart over the whole distance of interest.
5. Open the experiment file called L11E2-2 to display the force vs. position axes.
6. Zero the force prob and motion detector with the same supported loosely and un-stretched.
7. Verify that motion detector is set to "Reverse Direction", so that toward the detector is positive.
8. Begin graphing force vs position as the cart is moved slowly towards the motion detector until spring is stretched about 0.6 m.

EXPT 2
1. Use same set up as above.
2. measure the mass of the cart
3. Under control, new calculated column, enter a formula that would allow you to calculate the kinetic energy of the cart at any point.
4. Be sure that motion detector sees the cart over the whole distances of interest.
5. Make sure that x-axis of your graph is "position". Zero the force porb with the spring hanging loosely. Also zero the motion detector, so both the forced and position are zero in the starting position. Then pull the cart along the track so that the spring is stretched about 0.6 m from the un-stretched position.
6. Begin graphing. and releasing the cart, allowing the spring to pull it back at least to the un-stretched position.
7. Find the change in kinetic energy of the cart after it is released from the initial position to several different final position. Use the Analysis, Examine feature of the software. Also find the work done by the spring up to that position. Record these values of work and change in kinetic energy in a table determine from your graph the position of the cart where it is released and record in in the table.

Data:

( Above is the graph that shows time, force, position and kinetic energy. When the cart started to accelerate toward spring, the motion sensor calculate the change in distance. Furthermore, kinetic energy column was calculated by input equation of 0.5*m*v^2, in which mass is given and velocity is based on the motion sensor.  

Conclusion:

In this experiment, we released spring to see how fast the cart we accelerate and distance it traveled. By using force prob and motion sensor, it capture wave very rapidly. So we can have an accurate data. We did find the area under the curve from different energy and work. Since work and kinetic energy are related, we can set them equal to each other to measure our answer come out correctly. The one only error I know is that between wheels and track there's little kinetic friction acting on it. It will affect the speed of the cart, which can ultimately affect work(force * distance). Since work don't require what happen between wheels and track, the final answer will come out slightly different.