Automated measurement of speed
I can outline how radar guns in speed cameras are used to measure speed and use light gates to measure the speed of a moving object.
Automated measurement of speed
I can outline how radar guns in speed cameras are used to measure speed and use light gates to measure the speed of a moving object.
These resources will be removed by end of Summer Term 2025.
Lesson details
Key learning points
- A light gate measures the time for a card of a fixed length to pass through it.
- A radar gun measures changes in the frequency of reflected waves to measure speed.
- A motion sensor can use reflected ultrasonic wave timings to measure changes in distance to determine speed.
Keywords
Speed camera - A speed camera is used to measure speed of vehicles on roads. It captures images of any vehicle exceeding the speed limit of the road.
Radar gun - A radar gun uses shifts in the frequency of reflected radio waves to measure the speed of objects.
Light gate - A light gate can be used to measure speed. It uses an infrared beam to turn a timer on and off as an object passes through.
Common misconception
Travelling at exceptionally high speed through a speed camera means that it will not be able to measure your speed accurately and so it will not trigger.
Tell pupils that speed cameras use radio waves which travel at 300 000 000 m/s. They can accurately measure the speed of objects travelling at thousands of metres per second.
To help you plan your year 10 physics lesson on: Automated measurement of speed, download all teaching resources for free and adapt to suit your pupils' needs...
To help you plan your year 10 physics lesson on: Automated measurement of speed, download all teaching resources for free and adapt to suit your pupils' needs.
The starter quiz will activate and check your pupils' prior knowledge, with versions available both with and without answers in PDF format.
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The assessment exit quiz will test your pupils' understanding of the key learning points.
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Explore more key stage 4 physics lessons from the Measuring and calculating motion unit, dive into the full secondary physics curriculum, or learn more about lesson planning.
Content guidance
- Risk assessment required - equipment
Supervision
Adult supervision required
Licence
Starter quiz
6 Questions
car on a motorway -
70 mph
person walking -
1.5 m/s
snail moving across floor -
10 cm/minute
space station orbiting Earth -
7.7 km/s
sound wave in air -
330 m/s
Exit quiz
6 Questions
light gate -
sends signals to a timer when a passing object cuts its infrared beam
motion sensor -
sends out sound pulses and the reflections from an object are detected
radar gun -
uses changes in frequency of reflected waves to measure speed
speed camera -
takes photos of road vehicles a short time apart