Speed and Velocity

• A rate is: – Quantity/time

• It tells us:– How fast something is moving– How much something changes in a given time

• Motion is relative– Everything moves– Things at rest on earth move relative to the Sun and

Stars

• A vector is a quantity with both– Magnitude (size)– Direction

• Scalar is – A quantity with Magnitude only

• Position - Separation between an object and the reference point.– It is a vector (has size and direction)– A reference point must be chosen

• Distance– Total distance traveled – no direction

• Displacement -where you are compared to where you started.– It is a vector.

– Equation: d = df - di

• Speed measures– How fast something is moving– It is the rate at which distance is covered– It has no direction– It is measured in terms of Units of

distance/Units of time

• Average speed– Total distance/time or v = d/t– It is an average– It is the whole distance– It is not displacement– It does not indicate different speeds and

variations

• Velocity tell us:– How fast– It is speed in a given direction– It tells us how fast and in what direction

• Constant velocity - Displacement/time

• Equation: v = df – di /t