1C10.20 - Constant Velocity Cart
To show that a cart traveling with no acceleration will travel with a constant velocity.
Set up the air track on a 5-ft cart, if available. Set up two timers and both photogates to measure time of individual cart passage (starts time on leading edge, ends time on leaving edge). Connect the air supply to the air track and connect the air supply to an on/off switch. Must level track first and re-check its level once the cart is pulled into the classroom. Its important that no acceleration is present on a horizontal track.
Be careful not to scratch the surface of the air track or of the carts used on the air track. Be sure to store the carts correctly when tearing down the demo (upside down without anything touching the surface that contacts the track).
Make sure the photogate timers are reset. Turn on the air supply and allow the system to come to full power. Place the cart on the air track and give it an initial velocity. Observe the measured time of the carts travel through the photogate. Both photogates should read the same value, regardless of the initial speed. To run it a second time, just make sure you reset the photogate timers.
An object that travels at a constant velocity has no acceleration. If you graph position vs time for an object traveling at a constant velocity, the position vs time graph would be a line with a constant slope equal to the velocity. The velocity vs. time graph would be a horizontal line with a y-intercept equal to the speed of the object. The acceleration vs time graph will be a horizontal line through the origin as there is no acceleration when an object travels at a constant velocity.