Speed

• Speed is a measure of the distance an object moves in a given amount of time.

• During a typical trip to school, your car will undergo a series of changes in its speed.

Speed

How could we measure the speed of an object?

What do we need to know?

How fast do you think I am going?

Speed

Speed = distance travelled

time taken

Speed

Speed = distance travelled

time taken

seconds

metres

Metres per second (m/s)

Speed

Speed = distance travelled

time taken

hours

kilometres

Kilometres per hour (km/h)

STARTER ACTIVITY:Distance, Speed and

TimeSpeed = distance (in metres)

time (in seconds)

D

TS

1. Laura covers 2000m in 1,000 seconds. What is her speed?

2. How long would it take to run 100 metres if you run at 10m/s?

3. Steve travels at 50m/s for 20s.

How far does he go?

S = D/T = 2000m/1000s= 2 m/s

T = D/S= 100m/10m/s= 10s

D = S x T= 50m/s x 20s= 1000m

Distance travelled?

What if we know the speed of an object and the time it moved for and need to calculate the distance travelled?

Distance travelled?

What if we know the speed of an object and the time it moved for and need to calculate the distance travelled?

Speed = distance

time

distance = speed x time

Time?

What if we know the speed and the distance travelled, how do we calculate how long (time) the journey took?

Time?

What if we know the speed and the distance travelled, how do we calculate how long (time) the journey took?

Speed = distance

time

time = distance

speed

triangle

s tx

d

Don’t forget!If the distance is measured in metres and the time in seconds,

-the speed will be in metres per second (m/s or m.s-1).

If the distance is in kilometres and the time in hours,

-the speed will be in kilometres per hour (km/h or km.h-1) etc.

EXAMPLES

Usian Bolt ran 100m in 9.58 seconds, what was his average speed?

10.43 m/s

Another example

A dog runs at a speed of 5 m/s for one minute. How far does he run?

Another example

A dog runs at a speed of 5 m/s for one minute. How far does he run?

Distance = speed x time = 5 x 60 = 300 m

Another example!

A car travels at 30 km/h and covers a distance of 900 km. How long did it take?

Another example!

A car travels at 30 km/h and covers a distance of 900 km. How long did it take?

Time = distance/speed = 900/30 = 30 hours

Now you try!

• Extension:

• How long does it take you to hop 5m?

• Can you use a metre stick and stopwatch to help calculate your average hopping speed?

• Also try:

-walking backwards

-hopping backwards