Projectile Motion Lab

Up Smooth Sailing Projectile Motion Lab Lift and Drag Angular momentum The football in flight

Objective:

In this lab you will investigate projectile motion with and without air resistance.  You will find the maximum range of a football with given initial velocity and the launch angles required for it to hit a target.  you will compare the hang times of the football for these different trajectories.

Procedure:

Open the Projectile Motion interactive animation.  

Position the canon 20 m to the left of the target, as shown below.

Choose the football projectile and give it an initial speed of 20 m/s.
 

Part 1:  Keep the initial speed of the projectile at 20 m/s.  Neglect air resistance

Find the maximum range of the projectile.  For this maximum range note the launch angle and the hang time of the football and estimate the maximum height of the football during its flight.

Find the two launch angles for which the projectile hits the target.  For these angles note the hang time of the football and estimate the maximum height of the football during its flight.

Fill in the empty cells in the table below.

Projectile speed: 20 m/s,  no air resistance
    Launch angle (deg) Maximum height (m) Hang time (s)
Maximum range        
Range 20 m      
Range 20 m      

Compare the two launch angles for the 20 m range to the launch angle for the maximum range.  What are the differences between these angles?
Compare the hang times.
What are the shapes of the trajectories?
Comment on your results. 

Part 2:  Keep the initial speed of the projectile at 20 m/s.  Do not neglect air resistance.  Choose the drag coefficient to be 0.5.

Find the maximum range of the projectile.  For this maximum range note the launch angle and the hang time of the football and estimate the maximum height of the football during its flight.

Find two launch angles for which the projectile hits the target.  For these angles note the hang time of the football and estimate the maximum height of the football during its flight.

Fill in the empty cells in the table below.
 

Projectile speed: 20 m/s,  no air resistance
    Launch angle (deg) Maximum height (m) Hang time (s)
Maximum range        
Range 20 m      
Range 20 m      

Compare these results with the ones obtained without air resistance.
Do the shapes of the trajectories change.  If yes, describe the changes.

Do the launch angles for the maximum range and the 20 m rage change?  If yes, describe the changes.

Do the hang times change?  If yes, describe the changes.

Part 3:  Assume the maximum initial speed with which a quarterback can launch a football is 25 m/s.

If the quarterback wants to get the ball to a receiver 30 m away in the minimum amount of time possible, what is the launch angle he has to use?

What is the minimum travel time of the ball?

Find answers to these questions for a drag coefficient of zero (no air resistance) and a drag coefficient of 0.5.