Momentum Lab Take 2

For your lab reports percent error can be positive or negative depending on whether the final momentum is less than ( negative error) or more than( positive error) the original momentum.

For runs where both carts were originally moving, the percent error can appear to be unreasonably large. This is because to find the original momentum we add one large number positive number to a large negative number and finding relatively small difference between the momentum to the window and the momentum to the door. A small percentage error in the large numbers can cause a large precentage error in the relatively small difference between the doorward and windoward momentums . Then we do the same to find the final momentum and compare the two. If we take the initial total momentum ( total meaning taking windoward as positive and dorrward as negative for example) minus the final total momentum and divide by the intial total and multiply by 100we can get a very large percent error, because we are dividng by the difference between two large but similar numbers. In order to get a real sense of the percent error, try taking the final total from the initial total and then dividing by the sum of the magnitudes of the initial doorward and initial windowward momentums, (i.e treating both windoward and doorward momentum as positive in the denominator). Of course multiply by 100 to get the error in percent.