Lab Help for Mousetrap car to answer a Student's question. I have posted it since some of the rest of you.may have a similar question............

A couple of things I noticed in your calculations……….

You have used your maximum distance of 10.1 m with the time we timed for 2 metres. That 3.9 seconds was for 2 metres not for 10.1 metres. So you need to replace all those large distances in your calculations with 2 metres (you wil find your values will become MUCH lower). Also you are calling your speed change in speed (you have used the triangle symbol in front of v) but what you are actually calculating is average speed.  It will not be change in speed…..it is average speed!!

For your Ek……..This is harder to explain to you over e-mail. You will probably use your average speed to calculate the kinetic energy since that is all we have to work with. HOWEVER, what we really would like to measure (in order to compare with the full potential energy in the trap) is maximum speed so we can get change in kinetic energy. SO you will find (once you fix your calculations) that your % efficiency will be VERY low. What I expect you to do in your report is explain why this is so (i.e. show an understanding of the difference between average speed and change in speed and why what you have calculated for kinetic energy is not really an equivalent comparison to the potential energy. As well you should talk about energy losses.