Experiment 10:

COLLISIONS-Simulation

PROCEDURE





For each collision, note the momentum and kinetic energy of the balls before and after the collision. Then check to see if these quantities are conserved by comparing total values.Reference your class notes and related sections in your text for background material on this topic. Open the Collision Worksheetand complete the header information.

A. Elastic Collision #1: Two balls of equal mass, one initially at rest

1.    Open the file Elastic Collision #1. This will launch the Interactive Physics simulation program.  You should see a window similar to Figure 10-1.

Figure 10-1:  Elastic Collision Number 1

2.    Click on the Run button in the upper left corner of the Interactive Physicswindow to begin the simulation. This button changes to Stop while the simulation is in progress. Practice running the simulation by alternately clicking on Run, Stop, and Reset,while observing the behavior of the balls and noting changes in the velocity windows above each ball on the screen.


NOTE: The down arrow at the left of each velocity window toggles the window between digital, graph, and bar modes. For this experiment, make sure your window is set to digital mode.
 

3.   In the space provided on the Worksheet, describe briefly what you observe regarding the motion of the two masses in Question 1.
NOTE: Formulas already have been entered for you in appropriate cells of the Worksheet (cells D23:E24 and D32:E33) to compute values for momentum and kinetic energy both before and after the collision. Zeros appear in these cells until data are entered in the related reference cells. Calculated values of momentum (P) and kinetic energy (KE) will appear after you enter the appropriate mass and velocity values in cells B23:C24 and B30:C31, respectively. 5.    Enter your conclusion (yes or no)regarding momentum and energy conservation for this collision in cells D35 and E35, respectively.   B. Elastic Collision #2: Two balls of equal mass; both moving to right. 1.    Close the Elastic-Collision 1 window and open the file Elastic Collision #2. You should see a window similar to the one you have been using, but now with mass B also moving with speed 1 m/s to the right.

2.    Again, Run the simulation several times and note the motion of the two balls.

3.    In Question 2 on the Worksheet, briefly describe the motion of these two masses both before and after the collision.

4.    Complete the energy/momentum table on the Worksheet to test if energy and momentum are conserved for this collision.

5.    Again, the momenta and kinetic energies are calculated automatically.  However, the totals must be computed by you.  In cell D55, enter the following:  " =  D53  +  D54".  Under the EDIT menu, COPY the contents of cell D55 and under EDIT...PASTE into cell E55.  Notice that the formulas are replicated faithfully.

6.    Repeat the same procedure for the totals in cells D61 and E61.

7.    Enter your conclusions regarding momentum and energy conservation for this collision in cells D64 and E64, respectively.

 C. Elastic Collision #3: Two balls of equal mass moving in opposite directions. 1.    Close the Elastic-Collision 2 window and open the file Elastic Collision #3.

2.    Again, Run the simulation and note the motion of the balls.

3.    Briefly describe the motion of these masses before and after collision in Question 3 on the Worksheet.

4.    Complete the energy/momentum table to test for conservation.
 

 NOTE: Don't forget to take account of the sign of the velocity (and momentum) for motion to the left. 5.    Enter your conclusion regarding the conservation of momentum and energy for this collision in cells D90 and E90. D. Elastic Collision #4: Two balls of unequal mass; one moving, one stationary 1.    Close the Elastic-Collision 3 window and open the file Elastic Collision #4. Mass A is set to 10 kg and Mass B to 5 kg for this experiment.

2.    Run the simulation several times and note the motion.

3.    Briefly describe the motion of these masses before and after collision in Question 4 on the Worksheet.

4.    Complete the energy/momentum table to test for conservation.
 

 NOTE: Be sure to use appropriate signs for the different velocities.
 
5.   Enter your conclusion regarding the conservation of momentum and energy for this collision in cells D117 and E117.


E. Inelastic Collision #1: Two balls of equal mass; one moving; one at rest.

1.    Close the Elastic-Collision 4 window and open the file Inelastic Collision #1.

2.    Runthe simulation and note the motion of these masses.

3.    Describe the motion of these masses before and after collision in Question 5 on the Worksheet.

4.    Complete the energy/momentum table to test for conservation.  In this case, you must compute the momentum of each mass before and after the collision.  The kinetic energy is still automatically calculated for you.

5.    In cell D133, enter the formula:  " =  B133*C133"  to find the product of mass and velocity.  Use EDIT...COPY on cell D133 and EDIT...PASTE into cells D134, D139 and D140.

6.    As before, also compute the totals of the momentum and the kinetic energy both before and after the collision for both masses, and enter in cells D135:E135 and D144:E144.

7.    Enter your conclusion regarding the conservation of momentum and energy for this collision.
 

 F. Inelastic Collision #2: Two balls of unequal mass; oppositely directed.
 
1.   Close the Inelastic-Collision 1 window and open the file Inelastic Collision #2.

2.    Run the simulation and note the motions both before and after collision.

3.    Describe the motion of these masses before and after collision in Question 6 on the Worksheet.

4.    Complete the energy/momentum table to test for conservation.

5.    Enter your conclusion regarding the conservation of momentum and energy for this collision in cells D172:E172.

6.    Answer Questions 7 through 11 on the Worksheet .

7.    Print out the Worksheet and turn it in to your Instructor.