Caitlyn+&+Stephany+Collision+Report

=1D Cart Collisions Lab= Date of Publication (Date of Most Recent Edits)


 * Participants**: List the participants in this experiment.
 * Purpose**: The purpose of this lab is to confirm the law of conservation of momentum.
 * Lab Documents**: [[file:1D Collsions.doc]]

This experiment was done through watching videos of collisions, and using these to collect data. In order to do that, we added points to the video that made a graph. The slope of certain parts of the lines gave us the velocity of that time range. We used this point- and- graph method to find the initial and final velocities of both the blue and red cars.
 * Brief Description of Experiment**:

This is an example of one of the graphs that was made by the date we collected using the points on the video.

See seperate (handed in) sheet
 * Data**:

For example, the calculation for our first collision looked like this:
 * Sample Calculations:**
 * //Momentum Calculation// || The momentum was calculated by multiplying both the masses of each car by the initial and final velocities of each car, then adding together the initial and final momentums to see if it was conserved or not.

Blue Car: Initial: 250 x 22.40 = 5600 Final: 250 x 0 = 0

Red Car: Initial: 250 x 0 = 0 5600 + 0 = 5600 Final: 250 x 19.16 = 4790

Initial (Red and Blue): 5600 + 0 = 5600 Final (Red and Blue): 5600 + 0 = 5600

These numbers were close, meaning momentum was conserved. || An example of the calculation:
 * //Kinetic Energy Calculation// || The kinetic energy was calculated by squaring the velocities (initial and final), then dividing the mass of the cars by 1000, multiplying by the product, and dividing by 2 (which comes from the 1/2 in 1/2mv​^2).

Blue Car: Initial: 22.4^2 x .25 / 2 = 62.72 Final: 0^2 x .25 / 2 = 0

Red Car: Initial: 0^2 x .25 / 2 = 0 Final: 19.16^2 x .25 / 2 = 45.8882

Initial (Red and Blue): 62.72 + 0 = 62.72 Final (Red and Blue): 0 + 45.8882 = 45.8882

For this specific calculation, since the numbers weren't all that close, this means that the kinetic energy wasn't the same before and after meaning that the collision was somewhat inelastic. ||

In this lab we found that momentum was conserved in the collisions, because after calculations were done, the initial and final momentums were close in number. We also found that some of the collisions were elastic, and some were inelastic by finding the initial and final kinetic energies in the collisions.
 * Results**:

1. Momentum is a vector quantity (it has direction associated with it). This is relevant for some of the collisions you analyzed. Which ones and why?
 * Lab Questions**:

In the collisons where there was movement in both directions, some of the velocity appeared negative, making some of the momentum values negative. When it is said that momentum has direction to it, it makes it possible to tell what direction something is moving in. In the collisions where the heavier car pushed the lighter one, there was a negative velocity because all of the momentum was being pushed into the lighter car.

2. Calculate the percent difference between the initial total momentum and the final total momentum for each collision. Which collision had the largest percent change in momentum?

According to our data, collision number 5 had the largest percent difference.

3. If you had not correctly scaled the video (the scale line was drawn incorrectly, for instance), it would have no effect on your data's ability to support or refute the law of conservation of momentum. Explain why this is so.

If the scale was wrong in the video, it would have an effect on the data collected. Although the data would be slightly off, it would still show that momentum was conserved, because everything would be calculated the same way.

4. You may have observed the carts slowing down as they moved across the track before the collision. Suppose you have two velocities for a cart; one just after it was pushed and one immediately before the collision. Which would be better to use to evaluate your prediction and why?

The velocity right before the collision would be the valid one, because that is the velocity that will have the most effect on the outcome of the collision.

We found that this experiment gave valid results because each collision showed that momentum was conserved. An improvement to the experiment may have been if we had done the collisions ourselves. That way, we would have measured everything ourselves, and that would have also answered some questions that we may have had as to how much the carts actually weighed (since it was hard to tell through the videos, even though it was written on the board).
 * Conclusion**:

To be assigned later.
 * A statement about whether you think that the experiment produced a valid and reproducible result and reasoning supporting your statement.
 * A suggestion as to why your experimental results differ from any accepted value or your expected result (if appropriate).
 * A suggestion for a simple improvement to the experiment. Think about what caused problems, measurement inaccuracies, or inappropriate simplifying assumptions and propose a change. A sketch may be helpful.
 * Reflection:** (to be completed by each group member individually).
 * Reflection:** (to be completed by each group member individually).

//Don't forget to link to your lab report from the lab reports page and to include a link to your lab report in your reflection.//