The velocity of an object is its speed in a particular direction. Velocity is a vector quantity because it has both a magnitude and an associated direction. To calculate velocity, displacement is used in calculations, rather than distance.
Unlike distance, which is a scalar quantity, displacement is a vector quantity. It includes:
Acceleration is the rate of change of velocity. It is the amount that velocity changes per unit time.
The change in velocity can be calculated using the equation:
change in velocity = final velocity - initial velocity
The average acceleration of an object can be calculated using the equation:
This is when:
If an object is slowing down, it is decelerating (and its acceleration has a negative value).
A car takes 8.0 s to accelerate from rest to 28 m/s. Calculate the average acceleration of the car.
final velocity, v = 28 m/s
initial velocity, u = 0 m/s (because it was at rest - not moving)
change in velocity, ∆v = (28 - 0) = 28 m/s
A car takes 25 s to accelerate from 20 m/s to 30 m/s. Calculate the acceleration of the car.
final velocity, v = 30 m/s
initial velocity, u = 20 m/s
change in velocity, ∆v = (30 - 20) = 10 m/s