Projectile Motion Simulation Page
(there are 2 simulations on this page)
Projectile Motion Simulation
c) PhET, PhET Interactive Simulations
.
1) Start with the "Intro" page of this simulation.
- Adjust the height of the cannon by dragging up or down on the silver pedestal.
- Adjust the angle of the cannon by dragging on the barrel end of the cannon.
- Adjust the initial speed of the projectile with the slider below the cannon.
- You can drag the bulls-eye target to where you think the object will land.
- You can also the object to be fired with the pull-down menu in the top right corner.
- Fire the cannon by clicking on the red button at the bottom green band.
- You can pan
in or out as necessary with the (-) (+)
buttons in the top left corner.
- You can clear the trajectory traces by clicking on the yellow button before firing again.
- The
human-sized David statue is just there as a
size reference.
2) Notice that with
the air resistance "turned off" :
- The trajectory is independent of what object you choose.
- The range (horizontal distance) is a maximum at some angle between 0 and 90 degrees. Can you predict what angle that is?
- For any particular initial angle, the range scales quadratically with the initial velocity.
Optional
(In Physics 1 - we will only calculate
projectile motion without air resistance)
3) Now "turn on" the
air resistance by selecting the checkbox in the
right-hand panel. Set the cannon angle to
45 degrees, set the pedestal height to 15
meters, and a high
initial speed of 30 m/s (67 mph).
Compare the trajectories for a baseball to a the
trajectory for a cannonball. Note the
deviation from the "ideal" trajectory with air
resistance "turned off"
4) Now repeat step
three above with a moderate initial speed of 10
m/s (22 mph). How big of a difference does
"turning on and off" air resistance make at this
lower speed compared to in step three?
Optional /
Advanced
(again, in Phys 1, we will only calculate
projectile motion without air resistance)
5) Move from the
"Intro" page to the "Lab" page, and you will be
able to adjust the size and mass of the object
to be fired. Remember (prove to yourself) that
neither size nor mass affect the projectile
motion when we neglect air resistance. But
with air resistance "turned on", you can now
play around and see how (and how much) the
surface-area-to-mass ratio affects the
trajectory in the presence of air resistance.
Monkey and Hunter Simulation
(c) Andrew Duffy, Boston University, Dept. of Physics
In the virtual demonstration below, you will perform the classic monkey-and-hunter experiment. In this experiment, you aim a dart gun at a target (the monkey) hanging in a tree. At the exact moment that you fire the dart, the monkey lets go of the tree and falls towards the ground. Will the dart hit the monkey? or will it pass above it? or below it? This experiment serves as a powerful demonstration of two important principles : (1) that all objects are "pulled downward" at the same rate by the force of gravity, and (2) motion along orthogonal axes (like horizontal motion and vertical motion) are independent.
1) Start by selecting the options : (Aim at the Monkey) , gravity = (10.0) m/s/s , and horizontal velocity = (50) m/s. Press (Play) to fire the dart at the target.
2) Observe that by
aiming directly at the dangling monkey you will end
up hitting it, if the monkey lets go of the tree
at the exact moment you fire the dart gun.
How can we understand this result?
3) Let's "turn gravity
off" by choosing gravity = (0.0) m/s/s.
Clearly, now, aiming directly at the monkey is the
correct strategy. The dart is undeflected by
gravity (with gravity set to 0.0 m/s/s) and the
monkey simply floats in place after letting go.
4) Now let's
incrementally "turn gravity back on" by choosing
gravity = (5.0) m/s/s. Both the dart and the
monkey are slightly pulled-down (deflected) compared
to their trajectories in step three above; but both
are deflected / pulled-down at the same rate, so the
dart continues to hit the monkey.
5) Bringing gravity back
up to full Earth gravity = (10.0) m/s/s, we can try
firing the dart with
different horizontal velocities. We will see
that at higher velocities, the dart reaches the
x-position of the monkey faster, and so will have
been deflected by the constant pull of gravity by a
lesser degree in this shorter time. But, the
monkey will also have fallen by a shorter distance
in this shorter time frame, so the dart still hits
the monkey.
[Optional /
Advanced]
6) You can also play around with aiming above
and below the monkey to see how those strategies
work. Notice that (with gravity turned on) if
the monkey does NOT let go of the tree, then you
would have needed to aim above the monkey in order
for the dart to reach the position the non-falling
monkey after it is deflected by gravity. Try
for example : g = 5.0 m/s/s , vx = 50 m/s , and (aim
high).
_______ Simulation
(c) ________.
The simulation below ....
1) Use
2) Use
3) Notice
(warning : these links will take you outside the UCSD webpage)
- Projectile Motion @ PhET
Interactive Simulations
- Monkey and Hunter by Andrew
Duffy
- Alternative : Monkey and
Hunter by Tom Walsh
- Alternative :
- Just for fun :
last updated : 08/22/18