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Inquiry: Acceleration of Gravity

Purpose: Using strobe effect to more accurately calculate gravity.


  • One meter above the ground we have a glass tube with a spigot valve to regulate how fast we drop the droplets of water.

  • You need to adjust the valve until you hear a drop strike the foil at the same instant that you see the next drop from the valve begins to fall.

  • When you have exactly set the valve, the time it takes a drop to fall to the foil is equal to the time interval between one drop and the next.

  • To most accurately determine the time between drops count the number of drops in 30 sec. This is the frequency. Take the reciprocal and you will have the period.

  • Record these in your notebook.

  • Since you know that d=½at2 for objects falling from rest. Rewrite this formula for acceleration.

  • Calculate gravity and % error.

  • Now repeat the experiment with the strobe light.

  • Use the strobe light to make the next drop appear to "freeze" just below the burette. This should help you be more accurate.

  • Again calculate your % error and record in your notebook.

Inquiry Questions:

  1. Discuss your results for the constant (g) with and without the use of a strobe light. Show the equation we used, how it was simplified, your calculations and percent error.

  2. If we counted 82 drops in roughly 30 seconds in this inquiry what would be the gravitational constant (m/s2)?