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

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Presentation on theme: "Speed. What is time?  A particular moment –10:25 and 15 secs  An interval of time –7pm to 7am."— Presentation transcript:

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? 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? 1.v = d/t 2.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? 1.v = d/t 2.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? 1.v = d/t 2.v = ? d = 800 miles t = 2.5 hrs 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? hours (45 minutes). What is its record-breaking speed? 1.v = d/t 2.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? 1.t = d/v 2.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. 1.t = d/v 2.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 1hr1 min 1hr1 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? 1.d = vt 2.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? 1.d = vt 2.d = ? v = 6.9 mph t = 54 minutes 3.d = 6.9 mph X 54 min 4.d = 372.6 mph/min (Does this make sense)  Must change minutes to hours –54 min X 1 hour = 0.9 hr 60 min 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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