Distance, Displacement, Speed and Velocity

Distance and displacement

• Distance is just how far an object has moved. It is a scalar quantity, so does not involve direction.
• Displacement is a vector quantity because it has a magnitude and a direction. It is distance in a certain direction.
• Displacement measures the distance from the start point to the end point in a direct straight line.
• If you walk 5m north and then 5m south, your displacement is 0m, but the distance travelled is 10m.

Speed and velocity

• Speed is a scalar quantity and just tells you how fast you're going. 
• Velocity is speed in a given direction, making it a vector quantity. 
• This means you can have objects travelling at a constant rate but still changing in velocity, if they are constantly changing direction.
• If you want to measure the speed of an object moving at a constant speed, you time how long it takes for the object to travel a certain distance.
• Using your measurements, use the formula Speed = Distance / Time to calculate speed.
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