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Linear Motion. What means of motion has done more to change the way cities are built than any other?. ELEVATORS!!. Neglecting Air Resistance. What if Aristotle neglected air resistance? Exposes simple relationships Paper, books, feather & coin demos. Motion is Relative.
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Linear Motion • What means of motion has done more to change the way cities are built than any other? ELEVATORS!!
Neglecting Air Resistance • What if Aristotle neglected air resistance? • Exposes simple relationships • Paper, books, feather & coin demos
Motion is Relative • Everything Moves! Even objects that appear at rest. • Move with respect to or relative to a reference point. • Book, Space shuttle • When we discuss speeds: Relative to Earth
Speed • Speed = change in distance/change in time • S=d/t • Per = divided by • Rate—divided by time • Primarily use m/s
Speed • If you ride a bike a distance of 5m in 1 sec, what is your speed? For 10m in 2 sec? For 100 m in 20 sec? • 5m/s for all of these
Instantaneous Speed • A car does not always move at the same speed. • Speedometer reads the speed at a specific instant or point in time. This is known as instantaneous speed. • Student demo-walk
Average Speed • Planning a trip • How long? • How far? • Car certainly does not go the same speed. • You only really care what the average speed will be • Avg Speed = total distance/time interval
Average Speed • If an indy car travels a distance of 180 miles in 1.5 hrs, what is the car’s avg speed? • 120 mph
Average Speed • The speedometer in every car also has an odometer that records the distance traveled. • If the odometer reads zero at the beginning of a trip and 35km a half hour later, what is the average speed? • 70 km/h • Would it be possible to attain this average speed and never exceed a reading of 70 km/hr on the speedometer? • No, If the trip starts and ends from rest the highest speed must be over the avg.
Average Speed • If a cheetah can maintain a constant speed of 25 m/s, it will cover 25 meters every second. At this rate, how far will it travel in 10 seconds? In 1 minute? • 250 m, 1500m