# Google Search Phet Projectile Motion to Get to Lab

Name:______

**Projectile Motion Lab**

Part 1: Go to ** and complete the activity. Print out or capture a screenshot of the completion form.**

**Part 2: Phet Sim**

**Google search “phet projectile motion” to get to lab**

**Case 1: Angle Held Constant**

- Which variables affect the projectile’s motion?

- Set the angle to 30° and no air resistance.
- Starting at an initial speed of 10 m/s and increasing by 5m/s intervals, fill in the following table. You can calculate the horizontal component of velocity using your knowledge of range and time.

Initial Speed (m/s) / Time of flight (sec) / Range (m) / Horizontal Component of Velocity (m/s)

10

15

20

25

30

- What happens to the range as you increase initial velocity?

- What happens to the time of flight as you increase the initial velocity?

- For the five entries listed above, write down the times for the projectile to reach its maximum height. (Hint: how does max height time compare to total time?)

**Case 2: Initial Velocity Held Constant**

- Set the initial velocity to 20 m/s and Complete the following table with varying launch angles

Launch Angle (degrees) / Time of flight (sec) / Range (m)

0

5

10

15

20

25

30

35

40

45

50

55

60

65

70

75

80

85

90

- On a sheet of graph paper, Graph the Range as a function of Launch Angle. To do this, plot the launch angle on the x-axis and the range on the y-axis. Once you have plotted all the data points, connect the points with a smooth line. Label all axis with units and provide a title to the graph.

- What angle results in the greatest range?

- How does the launch angle affect the time the projectile is in the air?

- How does the launch angle affect the range of the projectile?

- Components of initial velocity. Using the information you found in the table on the previous page, calculate the horizontal and vertical components of the projectile’s velocity. Remember, the horizontal velocity remains constant throughout the time of the projectile’s flight, but the vertical component is subject to (de)-acceleration of gravity. Therefore, you will be calculating vx and viy (initial in the y-direction). Also recall that for an initial velocity, vi, we have the formulae

20 / 0

20 / 15

20 / 30

20 / 45

20 / 60

20 / 75

20 / 90

- Describe the following components in terms of the initial velocity, vi.
- The Horizontal component of velocity when θ=0°

- The Vertical component of velocity when θ=0°

- The Horizontal component of velocity when θ=90°

- The Vertical component of velocity when θ=90°

**Case 3: Hit the target**

- Use a launch angle of 60° and an initial velocity of 30m/s. Your job is to predict the range of the projectile and place the target where you think the projectile will land. The following steps will guide you to the solution.

- What is the vertical component of the velocity?

- What is the horizontal component of velocity?

- Now that you have found the vertical component of velocity, how long until the ball reaches its maximum height? How long is the ball in flight in total?

- Now that you have found the total flight time, we can use this piece to calculate the range. The time of flight we found using the vertical component of motion is clearly the same that we can use for the horizontal component of motion. Thus, we have a vx and a t, so we can solve for dx (i.e. the distance the projectile travels in the x-direction, the range).

- Did it work? Yes or No. If not, how far were you off?

**Case 4: Air Resistance**

- Check the box for air resistance, set the drag coefficient to 5.0, and set the altitude to 0.

- With an initial velocity of 50m/s, play around with firing the projectile at various angles. Does an angle of 45° still give you the maximum range?

- If you said yes, try again. Try firing at an angle of 45° first, than do 40°, and 35°

- Complete the follow-up questions on the attached page.

Canestaro/CHS Physics