Conceptual Physics Phet Projectile Cannon Lab

Conceptual Physics PhET Projectile Cannon Lab

To be completed in your lab notebooks

Pre-Lab:

·  On a fresh piece of paper in your lab notebook write today’s date and the title of the lab. Don’t forget to continue the page numbers in your lab notebook.

·  Glue your “Pre-Lab” sheet at the top of your new page and complete the questions.

Procedure :

1.  Open up the University of Colorado, PhET Projectile Motion simulation available here: http://phet.colorado.edu/new/index.php. Spend a few minutes familiarizing yourself with the controls of the simulation. You can adjust the mass, angle and velocity of the cannon’s projectile using the screen at the right.

2.  Create a data table in your book that will allow you to record Angle, Velocity, Max Height, Range, and the Time it takes to fall for two trials. Note: In order to find the maximum height you will need to use the measuring tape!

3.  Notice that there is a target on the simulation. Find at least two situations that would allow you to hit the target with a pumpkin and no resistance.

4.  Record the variables and results in your lab notebook for your two trials.

5.  Glue your second table (“Actual” Effect of Variables) into your notebook on a separate page.

6.  Use the simulation to test your predictions from your table in the pre-lab. Fill in the “Actual” table with the variables and their actual effect on the motion of the projectile.

7.  Notice that if you click on the cannon you can raise it up onto a pedestal. Raise the cannon up to 10 m above the ground.

8.  Set the angle of the cannon to exactly 0 degrees. Make sure that the screen to the right shows 0 degrees exactly.

9.  Set the velocity of the cannon to 0 m/s and click on “fire.” Make sure the air resistance is off and notice how long it takes to fall.

10. Set the velocity to 10 m/s and click on “fire” and notice how long it takes to fall. Set the velocity to 20 m/s and click on “fire” and observe.

11. If you have not already, try experimenting with the air resistance button and observe the effects on the projectile’s path.

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12. If you have not already, try experimenting with the different projectiles (pumpkin, tank shell, etc.) and observe the effects on the projectile’s path.

Analyzing:

?Underneath your data table, write “Analyzing” and you will answer the questions below in complete sentences. Don’t forget to number your answers!

1.  When the cannon was set to 0 degrees, what did you notice about the time it took the projectile to fall when it was shot off the pedestal compared to the time it took to fall straight down?

2.  List and explain the predictions that you found to be incorrect after playing with the simulation.

3.  Name at least two things that surprised you about projectile motion after you played with the simulation.

4.  You should have found that launch angle is a key variable.

a.  What angle causes the largest height?

b.  What angle causes the largest range?

5.  Do you think this simulation is entirely accurate? Why or Why not?

6.  If a projectile is shot at 0 degrees, does the velocity at which it is shot affect how long it takes to fall? Why or why not?