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Speed

Speed. D. Crowley, 2007. Speed. To be able to calculate speed, and to be able to predict how the forces acting upon an object will affect the speed. Question. Some year sevens ran to the end of the field How fast were they running at?

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Speed

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  1. Speed D. Crowley, 2007

  2. Speed • To be able to calculate speed, and to be able to predict how the forces acting upon an object will affect the speed

  3. Question • Some year sevens ran to the end of the field • How fast were they running at? • What extra information would you need to answer this question?

  4. What is Speed? • What is speed? • What is it measured in? • How can we work out someone’s speed? • You have five minutes to discuss with your partner the above questions…

  5. Speed • Speed is a measurement of how quickly something is traveling at, which can be in m/s; km/h; mph; cm/year etc… • To work out the speed of something, you need to know the distance covered and the time it took to get there • So speed = distance / time • E.g. 30mph = 30 miles traveled in 1 hour • E.g. 10m/s = 10 meters traveled in 1 second • E.g. 1cm/year = 1 centimeter traveled in 1 year

  6. Speed Formula Distance (d) Speed (s) Time (t)

  7. Examples Distance Speed Time • Jack ran 100m in 12 seconds. What speed was he traveling at? • Jack then ran 100m again, but this time it was much more windy, and it took him 15 seconds. What was his new speed, and why was this different? • My car was going at 50mph for 1 hour. How many miles did I travel • My car was going at 50mph, and I traveled 20 miles. How long did this take me?

  8. Examples Distance Speed Time • Jack ran 100m in 12 seconds. What speed was he traveling at? Speed = 100 / 12 = 8.34m/s • Jack then ran 100m again, but this time it was much more windy, and it took him 15 seconds. What was his new speed, and why was this different? Speed = 100 / 15 = 6.67m/s (more air resistance) • My car was going at 50mph for 1 hour. How many miles did I travel Distance = 50 x 1 = 50mph • My car was going at 50mph, and I traveled 20 miles. How long did this take me? Time = 20 / 50 = 0.4 hours (24 minutes)

  9. Speed • How can we measure which is fastest – running backwards, running sideward; skipping or running normally? • Produce a results table to collect your speed data for the four different running styles

  10. Speed • Using your data work out your speed (from the average time) and graph your results... Speed = Distance ÷ Time • Your graph should be a bar graph as the data we have is categoric – it falls into distinct groups

  11. Forces & Speed • How do forces affect speed? • What happens when you travel very quickly (i.e. on a motorway in the car) • What is it so much effort for a rocket to take off into space? • Why is it more fun to be going downhill on your bike, rather than uphill?!

  12. Forces & Speed • Forces can affect speed, both positively and negatively • Forces can help move objects, i.e. a car engine delivers a force to turn the wheels of a car, moving it • For example, cycling downhill is easier than uphill as gravity is helping pull you down Bike 1 traveling steadily at 10mph - engine is working against slight air resistance Bike 2 traveling steadily at 100mph - engine is working very hard against large air resistance

  13. Forces & Speed • The opposite is true of space rockets, which must fight gravity to escape the Earth • As you go very quickly you also experience more friction (increased air resistance, which causes you to slow down) • Different surfaces also have more / less friction - think about what is easier to run on, carpet or ice? Bike 1 traveling steadily at 10mph - engine is working against slight air resistance Bike 2 traveling steadily at 100mph - engine is working very hard against large air resistance

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