4.5.6.1.1 Distance and displacement/ speed/velocity

distance

how far an object moves, does not tell us direction

scalar quantity

displacement

tells us the distance an object moves in a straight line

from the start to the finish point

must include the direction and magnitude

vector quality

speed

distance object travelled in a given time

scalar quantity

no direction

equation for speed

*distance travelled* = *speed* × *time* 

*s* =*vt*

distance, *s*, in metres, m \n speed, *v*, in metres per second, m/s time, *t*, in seconds, s

typical speeds

waking/running/cycling/car/ train/aeroplane/sound

walking ̴ 1.5 m/s \n running ̴ 3 m/s \n cycling ̴ 6 m/s.

car on main road - 13m/s

fast train in UK 50m/s

cruising aeroplane- 250m/s

speed of sound in air= 330 m/s

factors that speed is dependent on

a younger, fitter person will usually be able to achieve a faster speed than an older or unfit person

on the terrain- people move more rapidly on flat ground than uphill

distance travelled- people that run faster at beginning tend to slow down

average speed

average speed= total distance/ total time

work out total distance and total

velocity

speed in a given direction

vector quantity 

magnitude and direction 

 equation for velocity

velocity(m/s)= distance/ time

velocity in a circle

even though car is moving at a constant speed its direction is constantly changing

means velocity is changing

==if an object moves at a constant speed in a circle then its velocity is constantly changing even though its speed is constant==