# First Project, 141/121

Your first project is a collaborative project between 2- 4 students. Please don’t do it alone. If there are 5 (or more) students who want to work together, you can collaborate, but do two different activities and split up the names between the two activities. We take data during class in week 2 or 3, meeting at Via Carta downhill from Baker Science. You can also take data outside of class. The project is due the following week.

The activity needs to be something that is somewhat physically demanding. For instance, move yourself or something relatively massive rather than throw a ping pong ball.

The project must include kinematic data from a video you take. It’s best if the camera/phone is mounted so that it doesn’t move around! You will make graphs of x <-> t, v<-> t, a <-> t. You may find that the displacement graphs are beautiful, the velocity graphs are a little noisy and the acceleration graph is a mess. you will need to estimate acceleration from finding the rate of change in the v <=> graph. for instance. You will very likely need to make your acceleration graph by hand – taking the slope of the v <-> t graph, as they did in the “Smarter Every Day” Video measuring the acceleration of the grasshopper. Additionally, make a graph of energy vs time. Which energies are changing? Graph all of them. If there is both kinetic and potential energy changes, put both of these energies on the graph as well as total energy on the same graph. Use this graph to find power as a function of time. You might want to graph P <=> t, or just state where power is greatest and estimate this power.

Depending on what you do, you might want to calculate momentum (for instance if there is a collision on a skateboard), or force.

I would like each project report to have the following:
1) A narrative of what you did
2) A drawing depicting the activity and screen shot(s) from the video
3) Raw data of position vs time as taken from the video. You don’t have to give me a complete sent… I’ve seen pages of wasted paper from this. Maybe just include a half page of rows… or make it small enough to fit on one page. But make sure you keep your data on your computer.
4) kinematic graphs vs time of displacement, velocity and acceleration. Make SCATTER graphs showing data points. Don’t allow the computer to make a line. You can make a line yourself if you like with a pencil to show trends. We make scatter graphs, because these are the data points that we know. A line implies that we know what’s happening between the data points… we can decide that later.
5) Make an energy <=> time graph for all energies. Put all the energies on the same graph, and also have a trace for total energy. You can use this graph to find when the power is the greatest, and when energy is conserved.
6) Short discussion of what knowledge came from your activity? Are your results consistent with what you expected?
7) In the three kinematic graphs and energy graph, please label important moments like when something left the ground, at the top of the trajectory, when you let go of something, etc. Please put these graphs vertically above each other with the times lined up with x-t at the top, then v-t, then a-t.
***8) you will very likely find that your acceleration and power graphs (if you make a P <=> t graph) are very noisy… this is likely because the tiny uncertainties in displacement are magnified because we’re dividing by a tiny time increment. Please see the smarter every day video again if you need to. Notice that they had the same problem. However, they solved it by fitting a line to the area of interest and taking the slope manually. You will need to do this, possibly in several places. You will have to think about what is going on. NOTE!: Typically, students take three or more tries before they actually do this: manually put in a trend line and look at how slope changes. It is important that you look at your data and ask yourself if what you’re doing makes sense. Are the accelerations, power something that seems reasonable?
9) Make a FBD to explain what you see happening at all the interesting parts of your activity.
10) Throughout calculations be mindful of how accurate your values can be. I won’t make this an exhaustive lesson in significant figures, but please ask yourself how precise you really think the velocity is when Excel spits out 4.327564 m/s. How accurately did you measure the distances? times? Please allow this to reflect in your level of implied precision.