Kinematics

Define speed, its equation and SI base unit

The rate of change of distance

v = d / t

v = speed, ms^-1

d = distance, m

t = time, s

How is average speed measured?

Work out the speed over a specific time interval

Define distance

The total length covered

Define velocity, its equation and its SI base unit

The rate of change of displacement

v = s / t

v = velocity, ms^-1

s = displacement, m

t = time, s

Define displacement

The distance covered in a given direction

Define acceleration, its equation and SI base unit

The rate of change of velocity

a = v / t

a = acceleration, ms^-2

v = velocity, ms^-1

t = time, s

Describe a distance time graph with notes

x axis = time/s

y axis = distance/m

m = speed, ms^-1

• The gradient cannot be negative because direction isn’t accounted for.

Describe a displacement time graph with notes

x axis = time/s

y axis = displacement/m

m = velocity, ms^-1

• The y intercept determines the starting position.

• When the gradient becomes positive or negative, it determines whether the object is moving away from/towards the starting position. NOT whether its accelerating or decelerating.

• When the gradient increases rapidly then slows down the object is decelerating, when the gradient increases slowly but speeds up rapidly , the object is accelerating.

Describe a velocity time graph with notes

x axis = time/s

y axis = velocity/ms^-1

m = acceleration, ms^-2

• area under graph = displacement, m

• The y intercept determines the stating velocity.

• When the gradient becomes positive or negative, it determines whether the object is accelerating or decelerating.

Define instantaneous speed/velocity/acceleration

The speed/velocity/acceleration measured over a very short period of time