Projectile Lab

Part 1: Hands on Lab

Purpose

To predict the path of a projectile and calculate where it will hit the ground.

Materials

• marble or small ball
• meter stick
• stopwatch
• ruler
• book
• carbon paper
• white paper
• tape

Procedure:

1. Set up the equipment so it matches the diagram. Using a ruler with a groove in the backside will make the launch easier.
2. Measure how far the marble will move on the table top. Be sure that the distance is not too short, so you get an accurate time measurement, but also not too far as that would cause the marble to slow considerably due to friction.
3. Time how long it takes the marble to roll across the table top. Calculate the launch speed in the table below.
4. Repeat step 3 two times. Find the average launch speed.
5. Use dy = viy*t + ½ ay*t2 to find the time the projectile is in the air.
6. Use dx = vix* t to find an estimated horizontal distance of the projectile.
7. Measure this distance on the floor using a meter stick and tape a sheet of white paper at the location, with the estimated location of the projectile marked on the paper with a pencil.
8. Put a sheet of carbon paper, face down, on top of the white paper. Launch the projectile.
9. Check the white paper to see where the marble landed.
10. Answer the questions below.

Data

Table 1: Calculated launch speed

Calculations

Time projectile is in the air: dy = viy*t + ½ ay*t2

Estimated horizontal distance of the projectile: dx = vix* t

Analysis and Conclusions

1. Measure the distance the marble went from the edge of the table.

2. Calculate the percent error between the predicted distance and the actual distance the marble traveled.

3. What errors might have been made in the activity?

4. Did the horizontal velocity change while the marble was in the air? Explain.

5. Did the vertical velocity change while the marble was in the air? Explain.

Part 2: PhET Simulation - optional extension activity

Purpose

To predict how projectile paths are affected by changing the object, angle the object is launched, initial speed, mass of the object, height of launch, and presence of air resistance.

Materials 

An internet connected computer

Procedure

1. Open up the PhET Projectile Motion Simulation.
2. Beginning with the golfball, run the simulation to fill in the data table below.
3. If a value is given in the table, adjust the settings to match the value. Once the needed values have been selected, select “Fire”.
4. The range, dx, and the time are given on the top of the page.
5. Use the tape measure to measure the maximum height, dy, or you can get this measurement from watching the height box at the top of the page during the launch.
6. Complete the Conclusions and Evaluation section below.

Data

Table 1: Projectile variables

Analysis and Conclusions

1. How did the time, distance traveled, and peak height compare with different objects?
2. Choose 3 objects in the simulation and launch each at 3 varying angles. Create a data table below.
3. What effect did the angle of launch have on the time, distance traveled (dx), and peak height (dy)?
4. Choose 3 objects in the simulation and launch each at 3 varying initial speeds. Create a data table below.
5. What effect did the initial speed have on the time, distance traveled (dx), and peak height (dy)?
6. Choose 3 objects in the simulation used in table 1 and launch each as you did before (with 45º angle and an initial speed of 18 m/s), however check the box “Air Resistance”. Create a data table below.
7. What effect did air resistance have on the time, distance traveled (dx), and peak height (dy)?