PHYS 2425 – Engineering Physics I

Projectile Motion

 

Leader: _____________________________  Recorder: ___________________________

Skeptic: _____________________________ Encourager: _________________________

 

Materials


Laptop

Mini DV camera with cable and power supply

Golf Ball

High Contrast Meter Stick

Black cloth for background (optional)

Tripod (optional)


Introduction

Projectile motion occurs when a free falling object has a non-zero initial component of horizontal velocity.  In this lab we will examine the motion in the x and y directions for projectile motion

 

Procedure

Part 1 Launch and Landing at Same Heights

1.  Set-up

      In this lab you will toss a golf ball at approximately a 45° angle above horizontal and record the motion with a video camera.  Position the camera so that you can see the entire path that the ball will travel.  To obtain accurate data, the camera should be facing forward (not at an angle) and should be aligned vertically.

      Place the meter stick so that it is visible in the camera and that it lies in the plane of motion of the projectile.

 

2.  Data Acquisition

Toss the ball as described above and observe its path, also known as the trajectory, with the camera.  Adjust the camera and the speed and angle of launch of the projectile so that you can see the entire trajectory of the projectile in the camera.  Use LoggerPro to record the trajectory with the camera.

 

Data Analysis

      Use the slider to position the clip so that you can just see the projectile in the air after being launched.  Click on the ball until just before it hits the table.  Try to click as accurately as possible to obtain good results.

 

1.  View the graph for the x position.

 

Q1)  Describe the shape of the graph of the x position.

 

 

Q2)  What does the shape tell you about the motion in the x-direction?

 

 

Q3)  Use the linear regression button   to add a best fit line to the graph.  Record the equation given by the fit.

 

 

Q4)  What does the slope you recorded in Q3) tell you?

 

Print and attach the graph.

 

2.  View the graph for the x-velocity.

Q5)  Describe the shape of the graph?

 

 

Q6)  What does the shape of the graph tell you about the motion in the x-direction?

 

 

Q7)  Does your answer to Q6) agree with your answer to Q2)?

 

 

Print and attach the graph.

 

3.  View the graph for the y position

 

Q8)  Describe the shape of the graph of the y position.

 

 

Q9)  What does the shape tell you about the motion in the y-direction?

 

 

Q10)  Use the curve fit button   to add a best fit quadratic to the graph.  Record the equation given by the fit.

 

 

Print and attach the graph.

 

4.  View the graph for the y-velocity.

Q11)  Describe the shape of the graph?

 

 

Q12)  What does the shape of the graph tell you about the motion in the y-direction?

 

 

Q13)  Use the linear regression button   to add a best fit line to the graph.  Record the equation given by the fit.

 

 

Q14)  What does the slope you recorded in Q13) tell you?

 

 

Q15)  Does your answer to Q12) agree with your answer to Q9)?

 

Print and attach the graph.

 

5.  View the graph of y-position vs. x-position

Q16)  Describe the shape of the graph.

 

 

Q17)  Use the curve fit button   to add a best fit quadratic to the graph.  Record the equation given by the fit.

 

 

E18)  You can also determine this equation from your fits to the x-position and the y-position.  Solve the equation you recorded in Q3) for the time.  Then substitute that expression for t in the equation you recorded in Q10).  Once you’ve collected like terms you have an equation for the trajectory of the ball.  Show your work in the space below.

 

 

 

 

Q19)  How does the equation you found in E18) compare to the fit you found in Q17)?

 

 

Summary Questions

S20)  Fill in the blanks with either uniform or accelerated.  In projectile motion the motion in the x-direction is ____________ and the motion in the y-direction is ___________.

 

S21)  What is the acceleration in the x-direction for projectile motion?

 

 

S22)  What is the acceleration in the y-direction for projectile motion?

 

 

S23)  Circle the correct answer.  In projectile motion, the motion in the x-direction is uniform/free fall.

 

 

S24)  Circle the correct answer.  In projectile motion, the motion in the y-direction is uniform/free fall.