Average velocity

If initial velocity and final velocity are known, average velocity can be calculated using the equation:

Average velocity = \frac{\text{initial velocity + final velocity}}{\text{2}}

Question

A school bus is travelling at 4 m/s.

Its velocity then increases to 12 m/s.

Calculate the average velocity of the bus over the journey.

Final velocity = 12 m/s.

Initial velocity = 4 m/s.

Average velocity = \frac{\text{initial velocity + final velocity}}{\text{2}}

= (4 m/s + 12 m/s) ÷ 2 = 16m/s ÷ 2 = 8 m/s.

The average velocity of the bus is 8 m/s.

There are two equations for average velocity:

curriculum-key-fact
Average velocity = \frac{\text{displacement}}{\text{time}}
curriculum-key-fact
Average velocity = \frac{\text{initial velocity + final velocity}}{\text{2}}

You decide which equation to use, depending on the quantities given in the question.