to create a lab simulation for students from a teachers perspective

Projectile Motion Lab Handout

Click on the “Projectile Motion Simulation” link to perform simulations in the setup

satisfying the given conditions.

Click on the Lab tab. Change the Gravity to 9.80 m/s2.. Keep the height of the cannon at ground

level.

Determine what angles you must have the cannon tilted at to have the cannon ball land at the

target 20.5 m away when you have an initial speed of 20 m/s using the simulation. Let the mass of

the cannon ball remain at 17.60 kg and the diameter at 0.18 m. Then use the Range formula

R= v0 2 sin(2θ) g

to verify the angles.

(R: Range, θ=angleof inclination.v0=initialvelocity¿

At 9 degrees the cannonball hits the target 20.5 m away. , θ=¿180

Use the Time, Range, and Height tool to determine the total amount of time the cannon was in the

air (slide the tool to the landing point to list the time the cannon took to reach the ground). The ball was in the air for a total of 1.03 seconds.

Now change to initial velocity to 15 m/s. Find the angle that will allow for the maximum horizontal

displacement when the object is launched at the same level it will land.

The angle that allows for a maximum horizontal displacement is 43 degrees with a displacement of

24.88 m

Now try changing the object to a different object (with a different mass and shape). Compare the

trajectory of both motions. You can try several different objects with various mass and size. Are

the trajectories different (different horizontal distance, different maximum heights, etc.) for each

of the objects? Does mass play a role in the launch given that the objects leave with the same

initial velocity?

No the trajectory is the same regardless of the shape and size or mass of the object due to the

initial velocity being constant and no air resistance.

Next we will study the effects of air resistance. Perform the following simulations to answer

the following questions.

Click on the eraser to clear the trajectories. With the cannon selected at the automatic diameter

setting, launch the cannon at an angle of 80 degrees. Next, click on the air resistance option to add

air resistance. Without change any other setting for the cannon, launch the cannon. Is there much

of a difference in the trajectories?

No there isn’t much of a difference in the two trajectories, however there is a minute difference in

the landing spots.

Now clear the trajectories using the eraser button. Increase the diameter of the cannon

significantly. Launch the larger cannon at the same angle without air resistance to observe the

trajectory. Next, launch the larger cannon at the same angle with air resistance. Is there much of a

difference in the trajectories. Does increased surface area affect the amount of air resistance on an

object?

Yes, the difference in landing spot of the trajectories is much more significant and noticeable since the

surface area has largely increased which also increases the total amount of air resistance on the object.

Conceptual Questions:

What is the shape of this trajectory?

The shape of this trajectory is a symmetrical half-dome or half-oval shape.

If an object is launched with a strictly horizontal initial velocity, what is the vertical component of

the initial velocity?

The vertical component is zero.

Will an object take longer, less, or the same amount of time to reach the ground if it is dropped

from rest rather than launched with a strictly horizontal initial velocity?

An object takes the same amount of time to reach the ground if it is dropped from rest to reach

the ground or if it is launched with a strictly horizontal velocity has zero acceleration and constant

velocity

With a strictly horizontal launch (with an angle of 0 degrees from the horizontal), how does the

initial velocity affect the trajectory (specifically the range)? Use the simulation to help you obtain

your answer.

With a strictly horizontal launch, as the initial velocity increases the range increases uniformly with respect

to the increase in initial velocity.