If a trolley moves freely down a slope, it appears to get faster as it nears the bottom. In this experiment you will measure the speed of the trolley at different points along the runway.


  1. Assemble the apparatus as shown. Connect the light gate to Input A on the datalogger and fix in position near the base of the runway. Measure and mark different start points for the trolley - they should be evenly spaced, with an equal distance between the points i.e. every 5cm from the light gate position upwards.

  2. Ensure that when released the trolley moves freely down the runway and that the interrupt card will cut through the light beam. Use an interrupt card which is 3cm in length.

  3. Click the Launch button to load the Timing software.

  4. Click on the Run Icon to begin logging. 

  5. Align the centre mark of the interrupt card on the trolley with position 1 and release the trolley. Check that no mishaps occur during its run. When the card has completely passed through the light gate the measured speed will be shown on the screen. If any mishaps occur, stop, delete, and repeat the measurement.

  6. Write down the distance between the light gate and the first start line in the results table or enter the value into a newly created column.

  7. Place the trolley at the second start position on the runway and repeat the procedure.

  8. Repeat the experiment with the trolley at position 3, 4, 5, etc, to build up a table of speed and distance results.
  1. The results can be saved, printed or copied into your report document as required.

  2. Use or transfer the data to plot an x-y graph of Speed at A (y-axis) against either the distance travelled or the reading number (x-axis). If available, trial fit a line to investigate which fits most closely to your data i.e. y=axb+c
  1. Compare the speed values at 5cm with those at at positions 2, 3, 4 etc. Is there a pattern in the way the speed changes with distance?
  1. Try repeating the experiment with the runway adjusted to a different tilt. Has the shape of the graph changed? Write a brief conclusion for this investigation.

  2. Does the mass of the trolley change the result? Load masses on the trolley to find out.

©1999 Data Harvest
Education		 Time and Motion Sensing Science