Download - Speed
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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.
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Speed
How could we measure the speed of an object?
What do we need to know?
How fast do you think I am going?
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Speed
Speed = distance travelled
time taken
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Speed
Speed = distance travelled
time taken
seconds
metres
Metres per second (m/s)
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Speed
Speed = distance travelled
time taken
hours
kilometres
Kilometres per hour (km/h)
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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
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Distance travelled?
What if we know the speed of an object and the time it moved for and need to calculate the distance travelled?
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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
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Time?
What if we know the speed and the distance travelled, how do we calculate how long (time) the journey took?
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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
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triangle
s tx
d
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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.
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EXAMPLES
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Usian Bolt ran 100m in 9.58 seconds, what was his average speed?
10.43 m/s
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Another example
A dog runs at a speed of 5 m/s for one minute. How far does he run?
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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
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Another example!
A car travels at 30 km/h and covers a distance of 900 km. How long did it take?
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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
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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