Directions Complete each section of the worksheet while using the Virtual Momentum Lab.

Transcription

1 Physical Science Virtual Momentum Lab Day One Directions Complete each section of the worksheet while using the Virtual Momentum Lab. Review the following equations for perfectly elastic and perfectly inelastic collisions. In a perfectly elastic collision, the following equation holds true: m 1 v 1(initial) + m 2 v 2(initial) = m 1 v 1(final) + m 2 v 2(final) m 1 = mass of object 1, m 2 = mass of object 2 v 1 = velocity of object 1, v 2 = velocity of object 2 In a perfectly inelastic collision, the following equation holds true: m 1 v 1(initial) + m 2 v 2(initial) = (m 1 + m 2 )v final m 1 = mass of object 1, m 2 = mass of object 2 v 1 = initial velocity of object 1, v 2 = initial velocity of object 2 v final = final velocity of both objects Virtual Lab Procedures Click on "Go to Lab." Select "Simulation" and then click on the "Proceed" arrow. Select "Perfectly elastic collision", and then click the "Proceed" arrow.

2 Experiment 1 Elastic Collision (e=1) Note: In a perfectly elastic collision, the elasticity coefficient is always 1. The elasticity is already set at 1 in the Virtual Lab and cannot be adjusted. After the collision, the two objects should bounce back in opposite directions. 1. Follow the directions on the Set Up Experiment screen to choose the masses. Record the masses (with units) you chose below (you pick) Note: You MUST include units ("kg" or "m/s") on all numeric values Click the "Start Experiment" arrow and then the "Proceed" arrow to get to the experiment table. Follow the "Procedure" on the left side to complete the experiment. Note: The value of the velocity of Ball B is negative because the value takes direction into account. Objects traveling to the left will have a negative velocity while objects traveling to the right will have a positive velocity. Record your chosen initial velocities (with units) below (your choice) Record the final velocities (with units) of the balls after the collision:

3 Answer the following questions based on the results of Experiment Explain what happened to each ball. Why you think it happened? Replay the experiment as many times as necessary to review 3. Replay the experiment and look at the momentum graph (upper right tab). What do you notice about the total momentum before and after the collision? Which of Newton's laws does this demonstrate? 4. What do you think would happen to the velocity of each ball after the collision if you set the masses and initial velocities of balls A and B equal? 5. If you set the mass of Ball A to twice that of Ball B and set their initial velocities equal, what do you think would happen to the velocity of each ball after the collision? How would the total momentums before and after the collision compare? Create a hypothesis. IF THEN (you will test it in the next section). Independent variable: The IF, what did you change on purpose? Dependent variable: The THEN, what did you measure as the outcome?

4 Experiment 2 Click on the Reset Experiment button to test your hypothesis from Experiment Record the mass, initial velocity, and final velocity of the balls. Record the masses (with units) you chose: (Ball A should have twice the mass of B) Record the initial velocities (with units) you chose: (They should have equal velocities.) Record the final velocities (with units) of the balls after the collision visible below the graph: Answer the following questions based on the results of Experiment Was your hypothesis from Experiment 1 correct? Why/why not? 8. If you set the initial velocity of Ball A to twice that of Ball B and set their masses equal, what do you think would happen to the velocity of each ball after the collision? Create a hypothesis. IF THEN (you will test it in the next section). Independent variable: The IF, what did you change on purpose? Dependent variable: The THEN, what did you measure as the outcome?

5 Experiment 3 Click on the Reset experiment button and test your hypothesis from Experiment Record the mass, initial velocity, and final velocity of the balls. Record the masses (with units) you chose: (They should have equal masses.) Record the initial velocities (with units) you chose: (v 1 should be twice that of v 2 ) Record the final velocities (with units) of the balls after the collision: Answer the following question based on the results of Experiment Was your hypothesis from Experiment 2 correct? Why/why not?

6 Experiment 4 Inelastic Collision (e=0) Note: In a perfectly inelastic collision, the elasticity coefficient is always 0. The elasticity is already set at 0 in the Virtual Lab and cannot be adjusted. After the collision, the objects should stick together and travel in the direction of one of the objects. Now we will test an inelastic collision, which is like colliding two giant wads of gum. Click on the "Reset Experiment" button. Select "Reset all values." Select the "Perfectly inelastic collision" button, and then click the Proceed arrow. 11. Record the mass, initial velocity, and final velocity for the balls. Record the masses (with units) you selected (you pick) Record the initial velocities (with units) you selected (your choice) Record the final velocities (with units) of the balls after the collision: Answer the following question based on the results of Experiment Explain in detail what happened in this perfectly inelastic collision.

7 13. Look at the momentum graph. What do you notice about the total momentum before (pre) and after (post) the collision? Final Analysis In real life, unlike virtual labs, collisions are NEITHER purely elastic nor purely inelastic, but instead fall somewhere in between. However, you can still classify many collisions as primarily elastic or inelastic. For example, hitting a baseball is a great example of an elastic collision, whereas catching the baseball is a nice example of an inelastic collision. 14. Explain why hitting/catching a baseball are great examples of each type of collision. 15. Describe another real world example for each type of collision. Real World Elastic Collision: Real World Inelastic Collision: