Speed is the rate of distance travelled. That is how much distance is being travelled in a bit of time. To be moving fast is to cover a __________ distance in a __________ period of time. While to be moving slowly is to cover a __________ distance in a __________ period of time.
Velocity is speed in a direction and so in some circumstances the words are interchangeable. We use the letter 'v' to represent both speed and velocity.
Rearrange the equation to fill in the gaps below:
so...
The SI units of length (distance) are __________ ,(__________) and the SI units of time are __________ ,(__________) so the SI units of speed are __________ per __________ ,(__________ ms-1).
If the speed changes during a period of motion then we must make sure we use the mean speed.