Question:Explain how Speed cameras that take two pictures work.
The speed camera takes two pictures 0.7 seconds apart. The car is travelling across painted lines on the road. By looking at how far the car travelled in 0.7 seconds, the car's speed can be calculated.
The speed camera uses radar to work out if a car is travelling too quickly. Only cars that are thought to be exceeding the speed limit have their photo taken.
The photo system is used instead of the radar measurement, because it is more reliable.