Speed and Velocity.

2 (a) state what is meant by speed and velocity.

Speed

Speed is defined as rate of change of distance. Its formula is distance/time. To put it simply, speed defines what distance a body covers in one second. So, if you say that something is traveling at a speed of 10m/s, it means that that object is covering a distance of 10m every one second. The standard unit for speed is m/s. The m stands for meters, which is distance while s represents seconds. Also, sometimes speed is stated as kilometer per hour, or km/h. From the formula, speed = distance/time, we can also deduce the formula for distance and time, by rearranging the equation. As the distance, is not in any particular direction, speed is a scalar.

Velocity 

Velocity is defined as rate of change of displacement. Its formula is the same as speed, which is distance/time. The units are the same too, m/s. The only difference is that as displacement has a specific direction, velocity is also in a praticular direction. This means that velocity can only be in a specific direction i-e if i say that the velocity of the car was 20km/h, the car must be moving with that speed in a particular direction only. Thus velocity is also a scalar quantity.