Introduction

This experiment uses a light gate and a data logger to measure the speed of a falling object dropped from different heights. A ping pong ball is ideal.

The experiment uses a light gate. This measures the time while the light is blocked off. The curtains or blinds may have to be drawn in the lab to allow the sensor to trigger properly.

Datalogger set up to record measurement	A diagram of the setup

Apparatus

light gate; datalogger; clamp stand; sandbag; metre rule; ping pong ball.

Method

• Set up a stand and clamp on the bench. Clamp the light gate into the stand. This has to be high enough to let the object you are dropping pass right through.
• Put a sandbag under the light gate to break the fall of the object.
• Place a metre rule vertically behind the stand.
• Measure the diameter of the object you have chosen to drop.
• Plug in the light gate to the logger. Set up the logger to measure the speed using one sensor.
• Enter the diameter you measured into the software.
• Practice dropping the object so it falls exactly between the "jaws" of the light gate.
• Start the timing software.
• Hold the ball 5 cm above the light gate and drop it through the "gate".
• Note the software is measuring the speed.
• Repeat the experiment four more times.
• Repeat all five readings for the object this time dropped from 10 cm, 15 cm, 20 cm, 25 cm and 30 cm. Stop if the object hits the light gate
  

Note: Treat the diameter of the ball as the length of the card when setting up the datalogger.

Analysis

Take results into Excel to produce table and graph.

Click here to see the graph showing a series of results.

Click here to open a worksheet.

For setting up instructions, click below on the datalogger you are using: