12
Friction
Subject: Physics
Sensor: SmartEye sensor
Aim:
To test the effect of friction on the speed/time of a ‘vehicle’ travelling down a ramp.
Overview:
The choice of using speed or time is partly dependent on the abilities and knowledge of the students. Because only one SmartEye sensor is used a
known length of card is required so that the speed can be calculated. Black Box starts timing when the front edge of the card passes the sensor and
stops timing when the back edge passes i.e. it times how long it takes the card to pass in front of the sensor. By knowing the length of the card and
how long it took to pass, the speed can be calculated.
Equipment required:
LogIT Black Box.
SmartEye light sensor.
Dynamics trolley, toy car or similar.
20cm matt black card.
Light source such as torch, lamp or similar.
Test track which can be raised to form a ramp.
Different materials to be placed on the track.
Hazards:
Students should be supervised at all times
Ensure the datalogger cannot come into contact with water or damp.
Always check your local regulations or the school advisory service such as CLEAPSS or
SSERC for guidance on the use of any hazardous material or source.
Setup:
1. Cut out a 20cm long piece of matt black card and attach it to the test vehicle.
2. Place Black Box about three quarters of the way down the track ensuring the card passes in front of the SmartEye sensor.
3. Place the light source opposite the SmartEye sensor forming a light ‘gate’.
4. Connect Black Box to the computer, start the datalogging software and select the timing function. Set up the software so that it knows you
are using a single light ‘gate’.