Measuring g with two photogates

Theory

A ball falls through two light gates. Each gate measures the instantaneous speed. By Torricelli’s equation, $v_2^2=v_1^2+2g\Delta h$, so $g=\frac{v_2^2-v_1^2}{2\Delta h}$.

What to observe

• The estimate appears next to the lower gate after the ball passes both.

Try this

• Move the gates and repeat (R resets).
• Switch gravity to the Moon’s value.

Also available in: Medindo g com duas fotoportas (Português) · Midiendo g con dos fotopuertas (Español)