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Speed

Speed. What is time?. A particular moment 10:25 and 15 secs An interval of time 7pm to 7am. Time. Measured in hours, minutes, days, years and seconds Metric only in science Always a number and a unit -25 secs. What is distance?. How far from one point to another Unit of length

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Speed

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  1. Speed

  2. What is time? • A particular moment • 10:25 and 15 secs • An interval of time • 7pm to 7am

  3. Time • Measured in hours, minutes, days, years and seconds • Metric only in science • Always a number and a unit -25 secs

  4. What is distance? • How far from one point to another • Unit of length • Metric only in science • Always a number and a unit – 25 m

  5. Speed • Measure of how quickly an object moves from one place to another • An object that is not moving has a speed of zero - 0 m/s • Distance traveled divided by the time taken • 90 miles in 1.5 hours = 90mi /1.5 h = 60 mph

  6. Velocity • Speed of the object and the direction of its motion

  7. Speed • Speed = v • v is for velocity (speed with direction added, traveled 75 mph south) • Distance = d • Time = t

  8. Problems A nascar driver has a car that is one of the fastest on the circuit. If it travels 600 miles in 4 hours, what is his cruising speed? • v = d/t • v = ? d = 600 miles t = 4 hrs 3. v = 600 mi/4 hrs 4. v = 150 mi/hr

  9. The fastest car on Earth, a German-made Thrust SSC, would win every Nascar race in America. If it takes 0.5 hours (30 minutes) to travel 380 miles, what is its speed? • v = d/t • v = ? d = 380 miles t = 0.5 hrs 3. v = 380 mi/ 0.5 hr 4. v = 760 mi/h (mph)

  10. The fastest train on Earth, the TGV from France, can travel at faster speeds than trains in the United States. During a speed test, the train traveled 800 miles in 2.5 hours. What is its speed? • v = d/t • v = ? d = 800 miles t = 2.5 hrs 3. v = 800 mi/ 2.5 hr 4. v = 320 mi/h (mph)

  11. Spirit of Australia, a hydroplane boat, made speed records by traveling 239 miles in 0.75 hours (45 minutes). What is its record-breaking speed? • v = d/t • v =? d =239 miles t = 0.75 hrs 3. v = 239 mi/ 0.75 hr 4. v = 318.67 mi/h (mph)

  12. How much time does it take for a bird flying at a speed of 45 miles per hour to travel a distance of 1,800 miles? • t = d/v • t = ? d = 1800 miles v = 45 mph 3. t = 1800 mi /45 mi/hr 4. v = 40 hrs

  13. A cheetah runs at 60 mph for a distance of 0.5 miles. How long does this take? Change answer to seconds. • t = d/v • t = ? d = 0.5 miles v = 60 mph 3. t = 0.5 mi/ 60mph 4. t = 0.008 hr • 0.008 hr x 60 min X 60 sec = 28.8 secs 1hr 1 min

  14. A comet is cruising through the solar system at a speed of 50,000 kilometers per hour for 4 hours time. What is the total distance traveled by the comet during this time? • d = vt • d = ? v = 50,000 km/h t = 4 hrs 3. d = 50,000 km/h X 4 hrs 4. d = 200,000 km

  15. A runner runs 6.9 mph for 54 minutes. What distance did the runner travel? • d = vt • d = ? v = 6.9 mph t = 54 minutes 3. d = 6.9 mph X 54 min • d = 372.6 mph/min (Does this make sense) • Must change minutes to hours • 54 min X 1 hour = 0.9 hr 60 min • d = 6.9 mph X 0.9 hr = 6.2 miles

  16. Time vs distance Graph • Shows distance traveled in relation to time traveled • Line sloping upward – steady speed • Change in upward slope = changing speed • Steeper = faster • Flat line – no motion • Downward slope – returning to start

  17. Time vs distance Graph • Slope of a distance/ time graph or a position/time graph will tell us the speed • Slope = rise/run • Slope = 60 miles/2 hrs • Speed = 30 miles/hr

  18. Average Speed • Average of all speeds over time traveled • Speed may not be constant • Distance to San Antonio, Texas • 1000 miles • Time traveled • 15 hours • Average speed equals • 66.66 mph

  19. Instantaneous Speed • Speed at a certain moment in time

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