Name: Date: Lab 3: Momentum - Virtual Simulations Visit the website: http://phet.colorado.edu/en/simulation/collision-lab, or open the application on the USB drive. Use the following instructions to help you explore the simulation and familiarize yourself with the controls: 1. Change the setting between 1 and 2 Dimensions and notice what changes. 2. Turn on velocity vectors. Drag the green arrow attached to one of the balls. What happens to the total kinetic energy of the system (lower left corner of screen)? 3. Turn on momentum vectors. Drag the green velocity arrows. What happens to the yellow arrows? Why? 4. Turn off the Reflecting Border and play the simulation. What happens? 5. Turn on the Momenta diagram, and run the default simulation. What do you think the pink arrow in this new window represents? 6. Move the elasticity slider all the way to the left, and run the default simulation. What happens during the collision? 7. Move the elasticity slider somewhere in the middle, and run the default simulation. What happens? 8. With momentum vectors turned on, drag the mass sliders. What happens to the yellow arrows? Why? 9. With momentum and velocity vectors turned on, click on more data. Adjust the green arrows and notice what happens to the data values. Drag one of the balls around the screen and notice what happens to the data values. 10. Adjust the time rate slider all the way to the left, then all the way to the right. What happens? Page 1 Name: Date: For the following questions you must create the scenario that is described, make a prediction about what you expect to happen during the collision, and then run the scenario to observe and record the actual results. Make sure that velocity and momentum vectors, show paths, and momenta diagram are turned on, reflecting border and center of mass are turned off. Include the dotted line paths in your diagrams. 1. A 1-dimensional, 100% elastic collision between 2 balls of equal mass and equal velocity. Diagram: Before Ball After (Predicted) Mass V - - P After (Observed) V’ P’ Predict Observe - - Predict Observe 1 2 System 2. A 1-dimensional, 100% elastic collision between 2 balls of equal mass but different velocity. Diagram: Before Ball After (Predicted) Mass V - - P After (Observed) V’ P’ Predict Observe - - Predict Observe 1 2 System 3. A 2-dimensiaonl, 100% elastic collision between 2 balls, one ball is stationary, the 2nd ball is approaching from some angle. Diagram: Before Ball After (Predicted) Mass V - - P After (Observed) V’ P’ Predict Observe - - Predict Observe 1 2 System Page 2 Name: Date: 4. A 2-dimensional, 0% elastic (inelastic) collision between 2 balls, one ball is stationary, the 2nd ball is approaching from some angle. Diagram: Before Ball After (Predicted) Mass V - - P After (Observed) V’ P’ Predict Observe - - Predict Observe 1 2 System 5. Create a scenario of your own choosing, that is different from all of the above. Be sure to write the scenario details below. Scenario: Diagram: Before Ball After (Predicted) Mass V - - P After (Observed) V’ P’ Predict Observe - - Predict Observe 1 2 System Page 3 Name: Date: 1-DIMENSIONAL COLLISIONS 6. Fill in the following table by calculating the missing values, using the formulas we have for conservation of momentum, and kinetic energy. Show your calculations on a separate sheet of paper. Remember, for elastic collisions: Ek = Ek’ ½m1v12 + ½m2v22 = ½m1v1’2 + ½m2v2’2 a. Elastic Collisions: Prepare the simulation with these settings for each of the following scenarios: 1-Dimensional Elasticity = 100% Velocity Vectors, Momentum Vectors, Show Paths, and Momenta Diagram = ON Reflecting Border, and Center of Mass = OFF M1 M2 V1 V2 Psystem V1’ V2’ Psystem’ (kg) (kg) (m/s) (m/s) (kgm/s) (m/s) (m/s) (kgm/s) 1 1.20 1.20 +1.50 -1.80 -1.80 2 2.40 4.80 +1.30 0.0 -.433 3 2.50 3.90 4 5.10 1.00 # .850 0.900 11.5 2.06 4.60 -4.60 b. Inelastic Collisions: Prepare the simulation with these settings for each of the following scenarios: 1-Dimensional Elasticity = 0% Velocity Vectors, Momentum Vectors, Show Paths, and Momenta Diagram = ON Reflecting Border, and Center of Mass = OFF M1 M2 V1 V2 Psystem M12 V12’ Psystem’ (kg) (kg) (m/s) (m/s) (kgm/s) (kg) (m/s) (kgm/s) 1 1.20 1.20 +1.50 -1.80 2 2.40 4.80 +1.30 3 1.50 5.50 +3.20 4 2.50 # 1.00 7.00 +0.80 0.0 Page 4 Name: Date: 2-Dimensional Collisions 7. Prepare a two-dimensional inelastic collision (0% elastic) involving two balls of different mass and different velocities, which are directed at some angle towards each other. a. Draw vector diagrams (right-angle triangles) for the initial velocity of each ball BEFORE the collision. You must calculate the angle using the x and y components of the velocity, which are found in the more data section of the simulator. b. Calculate the final velocity and final momentum of the system. Show your calculations on a separate sheet of paper. v12’ = ______________________________________ p12’ = _______________________________________ c. Draw a vector diagram for the final velocity of the system AFTER the collision. d. Check your answer by running the simulation. Were you correct? ___________________. e. Draw the Momenta Diagram for the system BEFORE and AFTER the collision. Page 5 Name: Date: 8. Prepare a two-dimensional 100% elastic collision involving two balls of different mass and different velocities, which are directed at some angle towards each other. a. Draw vector diagrams (right-angle triangles) for the initial velocity of each ball BEFORE the collision. You must calculate the angle using the x and y components of the velocity, which are found in the more data section of the simulator. Do not run the simulation yet! b. Draw a diagram that predicts the motion of the balls after the collision c. Calculate the final velocity and final momentum of each ball, and the system after the collision. Show your calculations on a separate sheet of paper. Do not forget the angles! v1’ = ______________________________________ p1’ = _______________________________________ v2’ = ______________________________________ p2’ = _______________________________________ psystem’= __________________________________ d. Draw a vector diagram for the final velocity of each ball AFTER the collision. e. Check your answer by running the simulation. Were you correct? ___________________. f. Draw the Momenta Diagram for the system BEFORE and AFTER the collision. Page 6