unit 2.1 physics - speed, distance and acceleration

gcse unit 2.1 physics

speed

speed

a measure of distance travelled over a given period of time

average speed

the speed over a journey - calculated by total distance over total time

instantaneous speed

the speed at a specific given time during the journey

scalar

means magnitude only and has no direction eg mass, distance, speed

vector

means magnitude and direction eg force, velocity, acceleration

distance-time graph: straight line

travelling at a constant speed

distance-time graph: horizontal line

the object is stationary

distance-time graph: curved line

speed is changing eg accelerating or decelerating

speed on a distance-time graph (calculation)

gradients: change in y/change in x

straight line equation

y = mx + c

velocity time-graph: straight line

constant acceleration/deceleration

velocity time-graph: curved line

non-constant/acceleration is not increasing

velocity time-graph: horizontal line

constant speed/velocity

calculation for distance in velocity time-graph

area under the graph

equation for acceleration/deceleration

change in velocity/time

what is the unit for acceleration

m/s2

alternative equation for acceleration

force/mass

thinking distance

the distance the vehicle travels in the time it takes for a driver to react to a situation and apply the brakes.

factors that affect thinking distance (6)

distractions (eg music), tiredness, alcohol, drugs, speed, individual reaction time

braking distance

the distance a vehicle takes to stop once the driver has applied the brakes

factors that affect braking distance (6)

speed, mass of car, state of brakes, road condition, tire condition, the weather

equation for stopping distance

thinking distance + braking distance