Final answer:
To investigate constant velocity with a motion detector, set up the detector at one end of a track, attach a force sensor to a cart, and push the second cart towards the detector. Compare the change in kinetic energy and the area under the force-displacement graph to determine if the velocity is constant.
Step-by-step explanation:
To investigate constant velocity with a motion detector, you can set up the motion detector at one end of a track and attach a force sensor to one of the carts. Push the second cart towards the motion detector using the force sensor, while the computer records displacement and velocity over time. By comparing the difference between the final and initial kinetic energies to the area of a graph of force versus displacement, you can confirm if they are the same, indicating constant velocity.