Changing Motion
This interactive 3D physics simulation models a dynamics cart moving on an adjustable track
while a motion sensor measures its motion. Students can change the initial position, initial speed, direction,
and track inclination and then compare position, velocity, and acceleration graphs
(the positive direction as away from the motion sensor).
a = -g sin(θ)
How to Use
- Adjust the left and right track heights.
- Set the cart's initial position and speed.
- Choose motion away from or toward the sensor (Use Reverse button & change the cart's initial position).
- Adjust the initial speed so the cart moves up and then down the inclined track.
- Click Start and observe the cart and graph.
- Use the "Pause" button to observe the positive or negative signs of velocity and acceleration.
- Switch between position, velocity, and acceleration graphs.
- Use Keep Graph, Reset, Change Controls, and Start again to compare different trials.
Note: This simulation assumes an impact time of about 0.15 s,
similar to a student stopping the cart by hand, to clearly show the change in the sign of acceleration
when the cart reaches near the end of the track.
What Students Learn
- Position: how the cart's location changes with time.
- Velocity: how fast and in which direction the cart moves.
- Acceleration: how the track inclination changes the cart's velocity.
- Graph interpretation: relationships among position-time, velocity-time, and acceleration-time graphs.
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