Lab #14 2D Collisions

Purpose: To observe and collect data on two dimensional collisions to explore the conservation of momentum and energy. For this experiment we will conduct two separate runs. One with two metal balls of equal mass and the second with one metal ball and one glass marble.

Procedure: We set up a camera directly above a glass table(so that there would be very little friction) to capture video of the collisions. These videos can then be analyzed in Logger Pro frame by frame.



For our first run we used a metal ball and a marble. We had one ball stationary and rolled the other one at an angle so that they would collide and bounce away in different directions each with its own new velocity and direction.

Using logger pro we went through the video frame by frame plotting points for each ball's position. We then created calculated columns for the x and y components of each ball and plotted each component on a distance vs time graph. We also set up a linear fit for each component before and after the collision.



Using each linear fit to find each components velocity before and after the collision we now calculated the momentum each ball and set up conservation of momentum equations for both the x and y components to see if momentum really was conserved.



For our second run we used two metal balls and conducted the same steps; capturing video, plotting points, analyzing linear fits to get velocities, and finally setting up and calculating conservation of momentum equations.





Our data safely confirmed the conservation of momentum during these two collisions, but what about energy? was it also conserved? To verify this we had to use our plotted points to set up new calculated columns for the kinetic energy(1/2*m*v^2) for the components of each ball and plotted each one on a graph of energy vs time.





We observed that for the energy to be conserved before and after the collision the potential energies for the x and y components acted similarly while the kinetic energy acted in an inversely proportional way.

Though our experiment had some small degrees of error this is most likely due to fundamental errors with the experiment. Such as the glass table not being completely frictionless and the curved camera lens distorting our video slightly.

Overall our experiment was a success in showing how both momentum and energy are conserved in our 2D collisions.