SPEED, VELOCITY AND ACCELERATION

SPEED

Speed is defined as the rate of change of distance with time.

Mathematically:

Where S and T refers to change in distance and change in time respectively. The S.I. unit of speed is meter per seconds (m/s) and speed is a scalar quantity.

UNIFORM SPEED

If the ratio is constant throughout the journey, the speed v is said to be uniform and can also be stated thus, if the rate of change of distance with time in a specific direction is constant then it is termed uniform speed.

Mathematically:

AVERAGE SPEED

Average speed is the ratio of the total distance travelled to the total time taken.

Therefore: average speed =

VELOCITY

Velocity is defined as the rate of change of distance with time in a specific direction. Velocity is therefore a vector quantity.

Normally, the word velocity is often used in place of speed, the only distinction between them is that speed is a scalar quantity while velocity is a vector quantity and the S.I. unit for velocity is meter per seconds (m/s).

UNIFORM VELOCITY

If the rate of change of distance with time in a specific direction is constant, the velocity is said to be uniform velocity.

ACCELERATION

Acceleration is defined as the rate of change of velocity with time.

Therefore:

Where; a = acceleration

v = final velocity

u = initial velocity

t = time

The S.I. unit for acceleration is meter per seconds square (m/s²)

Example:

A motorist travels from town A to town B at a distance of 145km in 3hr 45min.Find its average speed:

In km/hr

In m/s

Solution:

a)

Total distance = 145km

Total time = 3hr 45min

Total time = 3

b)

Total distance = 145km

145 x 1000 to meters = 145000m

Total time = 3hr 45min

The Penalty for Ignorance is Lack