Set up a timer using two photogates

Use this timer to measure the speed and acceleration of a cart.

Equipment setup

• 2×Photogates

  Use one of the following setups:

  • Wireless Smart Gate (PS-3225) with a Photogate Head (ME-9498A)
  • Smart Gate (PS-2180), connected to a PASPORT interface, with a Photogate Head
  • Two Photogate Heads connected to a digital interface

• Cart and track

• Cart Picket Fence (ME-9804)

  The Cart Picket Fence has three flags of different length. Adjust the height of the photogate so that the desired flag passes through the photogate beam, as shown below.

  

Set up the timer

1. Connect the Smart Gate, Wireless Smart Gate, or one of the Photogate Heads to Capstone.

2. Connect the second photogate through the appropriate means:

   • If your first photogate is a Smart Gate or Wireless Smart Gate, plug the digital jack of the Photogate Head into the Auxiliary Port of the Smart Gate. Locate the image of the Smart Gate in the Hardware Setup tool, click inside the yellow circle over the Auxiliary Port, and select Photogate from the list. (See below.)

     

   • If your first photogate is a Photogate Head, follow the same connection procedure to connect the second Photogate Head to the same digital interface.

3. Click Timer Setup in the Tools palette.

4. At the top of the Timer Setup tool, click the Delete button to delete the premade Smart Timer.
5. Select Pre-Configured Timer, then click Next.

6. Ensure that the appropriate photogates are selected from the list of available timing devices, then click Next.

   • If you are using a Smart Gate or Wireless Smart Gate with a Photogate Head, select channels 1 and 3.
   • If you are using two Photogate Heads, select both photogates.

7. Select Two Photogates (Single Flag) from the list of available timers.

8. Check the boxes for each of the measurements you want to be visible, then click Next.

9. Measure Flag Length and Photogate Spacing as described below. Enter these values into the appropriate text boxes, then click Next.

   • Flag Length: Equal to the length of the flag from end-to-end.

     

   • Photogate Spacing: Equal to the distance between the photogate beams.

     

10. Give the timer a custom name, or use the default name, and click Finish.

Record data

Click Record , then allow the flag to pass through the first photogate. The software records the speed after the photogate is blocked and then unblocked. A second speed measurement and the acceleration are recorded when the flag passes through the second photogate.