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A motion sensor collects data. At regular intervals it records the distance between itself and an object. If that object is moving towards, or away from, the sensor the distance data will change. You might like to experiment with this simulation of a motion sensor .

For 20 seconds a motion sensor is collecting data as a person moves backwards and forwards in front of it.

Here's the distance-time graph for that movement. Can you describe the person's motion? (the units are metres and seconds)

Distance Time Graph for the Motion Sensor

When was the person moving quickest? Calculate an estimate for this speed.

What was their lowest speed and when was this?