Interactive PhysicsTM
Free Fall Simulation - Initial Upward
Velocity
Discussion:
In this activity, you will use the Interactive
PhysicsTM program to simulate the motion of a ball in
free fallwith an initial upward velocity. When you first load the
simulation file, it is set up to simulate tossing a ball near the
surface of the Earth, where g = 10 m/s2 (approximately).
After investigating this motion, you will alter the value of g to
simulate tossing a ball on the Moon, where g = 1.63
m/s2.
Procedure:
- Double-click on the file "ip_free_fall_2_sim" which you will
find in your "Group Shared" folder. This will start the
Interactive PhysicsTM software and load the free fall
simulation. (Interactive PhysicsTM software may not be
available on all computers.)
- This
simulation is much like the "free
fall from rest" simulation, except that you can use the slider
to set the initial upward velocity of the ball. The allowed range
for this velocity is 0 - 40 m/s.
- Set the initial velocity, and click "Run" on the toolbar. The
ball will begin to move. Notice how the position, velocity, and
acceleration meters change as the ball moves. To stop the
simulation, click "Stop" (the "Run" button changes to a stop sign
while the simulation is running.). Note that you can start and
stop the simulation by alternately clicking "Run" and "Stop". To
reset the simulation, click the "Reset" button.
- Now, construct a data table in which you can record the
position, velocity, and acceleration for the ball for each second
from 0 seconds until it returns to its original position. (You may
use any initial velocity that you wish, but a multiple of 10 m/s
will make for easier calculations.)
- Reset the simulation and click "Run". When the timer is near 1
second, click "Stop". Use the frame advance buttons to move the
timer to precisely 1 second, and enter the data for position,
velocity, and acceleration in your data table. Click "Run" again,
and stop the simulation and record your data for the next second,
etc.
- Repeat steps 4 and 5 for a different initial velocity.
- Change the free
fall acceleration to approximate gravity on the moon (about
1.630 m/s2) and repeat steps 4 and 5 for tossing a ball
on the moon.
Questions:
- As the ball moves, what happens to its velocity? (Remember
that a quantitative description is superior to a
qualitative description...)
- As the ball moves, what happens to its acceleration?
- Suppose that you toss a ball upward on Earth and then toss the
same ball upward with the same initial velocity on the Moon. How
do the motions compare? (How is it the same, and how is it
different?)
- For one of you simulated ball tosses on Earth, calculate the
velocity and position of the ball for each second that it was in
the air. Be sure to show your neat, complete calculations. Compare
your calculated results with the simulation results.
- For the other simulated ball toss on Earth, calculate the
maximum height of the ball and the time that the ball will be in
the air. Be sure to show your neat, complete calculations. Compare
your calculated results with the simulation results.
- For the simulated ball toss on the Moon, calculate the maximum
height of the ball and the time that the ball will be in flight.
Be sure to show your neat, complete calculations. Compare your
calculated results with the simulation results.
last update October 4, 2001 by JL
Stanbrough