Explain the unit of speed in mechanics.

The unit of speed in mechanics is metres per second (m/s).

Speed is a measure of how fast an object is moving. In mechanics, speed is defined as the distance travelled by an object per unit time. The SI unit of distance is metres (m) and the SI unit of time is seconds (s), so the SI unit of speed is metres per second (m/s).

To calculate the speed of an object, we need to know the distance it has travelled and the time it took to travel that distance. The formula for speed is:

speed = distance ÷ time

For example, if a car travels 100 metres in 10 seconds, its speed is:

speed = distance ÷ time
speed = 100 m ÷ 10 s
speed = 10 m/s

It is important to note that speed is a scalar quantity, which means it only has magnitude and no direction. In contrast, velocity is a vector quantity, which has both magnitude and direction. The SI unit of velocity is also metres per second (m/s), but it includes a direction component, such as north or east.

In summary, the unit of speed in mechanics is metres per second (m/s), which is calculated by dividing the distance travelled by an object by the time it took to travel that distance.