Table of Mechanics Demonstration List of Mechanics Equipment & Supplies Lecture Demonstrations

# Constant Acceleration Car on Incline, 1G10.12

Topic and Concept:

Location:

Abstract:

A PASCO cart attached to a mass with a string running over a smart pulley is accelerated at a constant rate up an inclined track. A computer together with the PASCO interface can be used to measure the position, speed, and acceleration as a function of time.(Similar to 1G10.10)

 Equipment Location ID Number PASCO 1m Track ME, Cubby C4 PASCO 2.25m Track Floor Item - ME, North Wall PASCO Cart ME, Bay A5, Shelf #3 PASCO Smart Pulley w/Photogate ME, Bay A5, Shelf #2 A1.EQ.102 String ME, Bay B1, Shelf #2 Weight ME, Bay A1, Shelf #2 PASCO Interface Computer Floor Item, South Wall A1.EQ.100

Important Setup Notes:

• If using the PASCO interface is desired for the graphical output, a 24-hour notice is required.

Setup and Procedure:

1. Place the PASCO track on the lecture bench.
2. Put the green wood block on the table and set one set of legs of the track on top to give the inclined plane (see pictures).
3. Level the track by using the height adjustment screws on the track.
4. Place a small lead brick in front of the green wood block to keep the track from moving on the table when the cart accelerates.
5. Place the PASCO cart on the track, and add weight to it if desired. (The more weight, the more fiction between the cart and track)
6. Attach the PASCO smart pulley and photo-gate to the track.
7. Use the Velcro to keep the cart in place while the weight is attached and the string run over the pulley.
8. When ready, release the cart from the Velcro and observe it accelerating at a uniform rate. (Don't push the cart, this well give you the wrong data)

Optional Addition of the PASCO Interface with Computer:

1. Please refer to the PASCO Interface Computer, A1.EQ.100 page for general operations of the computer.

2. Before booting up the computer, make sure that the Photo-gate 1/4" plug is in Slot "A" of the PASCO Interface box.
3. Open the experimental setup file which is located on the desk top in the folder PASCO Interface under the file name ConsAcc.ds

4. Follow the above steps omitting the final step where the cart is released.
5. When ready record the data, click on "Start" at about the same time as when you release the cart.
6. If the auto stop feature is setup within Data Studio, the program will automatically stop recoding after the set time interval that was setup. If not, then just before the cart collides with the bumper click "Stop" in Data Studio (see plot below for an example or PASCO Interface Computer, A1.EQ.100 page).

Cautions, Warnings, or Safety Concerns:

• N/A

Discussion:

The net force acting on the cart is a little less than the weight pulling it down the track. There is also some friction in the axles of the car and in the pulley which acts to oppose the motion of the cart. The magnitude and direction of these forces remains constant throughout the demonstration. Therefore, by Newton's second law, since F = m*a = constant and since m is constant so must the acceleration remain constant. Because of this constant acceleration, we expect the position vs. time curve to be quadratic in time, and we also expect the velocity vs. time curve to be linear in time.

Videos:

References:

• N/A

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