10/29 Physics Class and homework due 11/5

Hi folks,

Today we spent time going over some of our previous problems and trying to make sure everyone is on the right track.

For homework, I want you to predict how far an object would go (d horizontal )  if it's shot parallel to the ground at the following heights and speeds.  Feel free to review your notes on this before you start.  Use d = 1/2 at^2 to find time.   Then use that time to find distance by using v=d/t.  (Use v=d/t to find horizontal distance travelled since there is NO acceleration horizontally.)

1.  5 m high  5 m/s

2.  10 m high  5 m/s

3.  15 m high 5m/s

4.  10 m high 10 m/s

5.  15 m high 30 m/s

Now, once you've done those calculations go to this website. https://phet.colorado.edu/en/simulation/projectile-motion.  When you get there click on the play triangle and then click "Intro".

Now use the website to see if your calculations are correct.  Set the appropriate velocities and heights and see if your calculations match the simulation. You can adjust the height by clicking and dragging on the tower the cannon is sitting on.  Be sure the cannon is shot at 0 degrees.  You can move the "target" to see the distance it traveled.  You can also use the measuring tape and/or the blue box that are located at the top middle of the screen.  Your calculations should be close to the results.  If not…check your math.

6.  Did your calculation match the sim?

7.  Put the initial speed to 0m/s.  Do the times still match the times you calculated for the different heights?  (Hint: they should.)

Under "Velocity Vectors" to the right, click on  "components" .

Shoot the cannon parallel to the ground (0 degrees).  You may want to put this on slow and feel free to pause the sim as the cannon ball is moving.

6.  As the pumpkin flies through the air, describe how the vertical velocity vector changes?

7.  As the pumpkin flies through the air, describe how the horizontal vector changes?

Now, turn on the "total" in the velocity vector box.  Pause the simulation as the pumpkin flies.  Notice carefully how the resultant velocity is a combination of the vertical and horizontal velocities.

Now shoot the cannon upwards at an angle of 60 degrees.

8.  As the pumpkin flies through the air, describe how the vertical velocity vector changes?

9.  As the pumpkin flies through the air, describe how the horizontal vector changes?