UNIT 2 LESSON 5: PROJECTILE MOTION
Visit the Website http://phet.colorado.edu/sims/projectile-motion/projectile-motion_en.html
I. Become familiar with the controls
A. The angle of the cannon changes if you mouse over the cannon and move it up and down.
For this experiment, use the green box on the right of the screen and set the angle to zero.
B. The cannon can be moved back and forth. Place the cannon as far to the left of the screen as possible.
C. Mouse over the wheel of the cannon. You can adjust the height of the cannon.
The heights for you to use are pre-set in Data Table 1 on Page 2.
To move the cannon to the correct height, extend the tape measure to the desired height and then
move the cannon until the center of the cannon is on the horizontal line.
D. Make sure "user choice" is selected in the green box. The mass and diameter will be the same for the
entire experiment.
E. Click on Fire. The "range" box at the top of the screen will show you the distance the object traveled,
also known as its horizontal displacement.
The "time" box will time the object from when it leaves the cannon until it hits the ground.
F. Click "Erase" to reset; the speed will remain the same.
II. Part I: Changing the Height of the Cannon
A. Make sure that the initial speed is set to 18 meters per second. The speed will be the same for all five
trials in Part I.
B. Make sure that the tape measure is positioned at the edge of the red circle that the cannon is sitting
on. Extend the tape measure straight up until it reads 15m.
C. Mouse over the wheel of the cannon and drag the cannon until its height matches the tape measure.
D. Make sure your angle is set to zero and your speed is set to 18 m/s
E. Click on Fire. Record the number from the "range" box in the Displacement Delta x (m) column.
Record the time on Data Table 1 on Page 2.
F. Click Erase and repeat steps A-E for each height listed on your data table.
III. Part III: Changing the Initial Velocity of the Object
A. The Initial Speeds for you to use are already filled in Data Table 2.
B. The Cannon Height will remain 15 meters: To move the cannon to the correct height, extend the tape
measure to the desired height and then move the cannon until the center of the cannon is on the
horizontal line. If the number in the "angle" box does not read zero, change it to zero.
C. Set the "initial speed" to 3 m/s and click "Fire"
D. Record the Displacement, ∆X, which is "range (m)" on the screen, in Data Table 2.
E. Record the time in Data Table 2.
F. Click "Erase" and repeat steps C-E for each initial speed listed in Data Table 2.
Data Table 1: Cannon height
Trial
Initial Speed m/s
1
2
3
4
5
Displacement Delta y (m)
18
18
18
18
18
Displacement Delta x (m)
Time
15
12
9
6
3
Data Table 2: Initial Velocity
Trial
1
2
3
4
5
Displacement Delta x
Initial Speed m/s Displacement Delta y (m)
(m)
3
15
6
15
9
15
12
15
15
15
Time
Average horizontal velocity
m/s
IV. Constructing Graphs: Follow the instructions and then fill in the blank for each statement. You may
use the Insert Chart function to construct your graphs.
A. Graph the Vertical vs. Horizontal Displacement from Data Table 1.
The higher the cannon, the _____________ the distance the object travels.
B. Graph the Vertical Displacement vs. Time of Motion from Data Table 1.
As the height of the cannon changes, the object spends ____________ time in the air.
C. Graph Time vs. Initial Speed from Data Table 2.
The intial speed is in the __________ direction; therefore, the ____________ will be the
_____________ for each trial.
D. Graph Initial velocity vs. Horizontal Displacement from Data Table 2.
The horizontal displacement depends on the ____________________________ of the object.