Physics 2.1 Distance Speed Acceleration

Distance speed time equation

d=s\cdot t

Distance (m), Speed (m/s), Time (s)

Speed from a distance time graph

Speed is equal to the gradient of the distance time graph

Speed at a given time for an accelerating object

Draw a tangent to the curve at the required time and calculate the gradient

Average acceleration equation

a=\frac{\Delta v}{t}
Acceleration (m/s² ) Velocity (m/s) Time (s)

Distance from a velocity time graph

Distance travelled is equal to the area under the velocity time graph

Stopping distance

The sum of thinking distance and braking distance

Effect of increased speed on stopping distance

Stopping distance increases when speed increases

Effect of speed on thinking and braking distance

Both thinking distance and braking distance increase as speed increases

Typical human reaction time

Between 0.2 seconds and 0.9 seconds

Factors affecting reaction time

Tiredness drugs and alcohol

Factors affecting braking distance

Wet or icy road conditions and poor tyre or brake condition