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Chapter 1

Chapter 1. Motion. Opening Question. How fast am I moving right now? Did you take into account the… plate shifting (1 in/yr) earth rotating (1038 mph) earth orbiting (67000 mph) galaxy spinning (43000 mph) universe expanding. Motion. How do we determine how fast something moves?.

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Chapter 1

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  1. Chapter 1 Motion

  2. Opening Question • How fast am I moving right now? • Did you take into account the… • plate shifting (1 in/yr) • earth rotating (1038 mph) • earth orbiting (67000 mph) • galaxy spinning (43000 mph) • universe expanding

  3. Motion • How do we determine how fast something moves? • Create a reference point because everything moves relative to everything else • All based on your perspective or point of view (POV)

  4. From Your POV • You are in a car on I-5 going exactly 70 mph. How fast is...

  5. Motion • How do we measure “fastness”? • Speed – the rate at which something moves • Rate – how much in a certain amount of time • Ex. mph, kph, or m/s

  6. Rates • Max is thinking about different units that can be used to express the speed of a car on a highway. Which units couldn’t be used to express the speed of a car?

  7. BugattiVeyron Super Sport(Fastest Car in the World)

  8. Motion • What is the difference between instantaneous and average speed? • Inst. is at a specific time and average is over a period of time • Average speed is the distance traveled (displacement) divided by time • Units: m/s or km/hr

  9. Speed (Math Triangle)

  10. BugattiVeyron - Practice • If the car went 2875 m in 25 s, what is its average speed? • If the car was going 115 m/s, how fast can it cover 500 m? • If the car was going 115 m/s how far does it go in 2 s? • Speed = 115 m/s • 258 mph • Time = 4.3 s • 230 m

  11. Speed – Basic Practice • What is the speed of a bike that travels 15 m in 2 s? • If a rabbit is going 3 m/s for 4 s, how far did it go? • How long did it take a koala bear moving at 0.5 m/s to climb a 20 m tree? • 7.5 m/s • 12 m • 40 s

  12. Speed – Advanced Practice • How much time would it take for the sound of thunder to travel 1,500 meters if sound travels at a speed of 330 m/sec? • 4.5 s • How much time would it take for an airplane to reach its destination if it traveled at an average speed of 790 kilometers/hour for a distance of 4,700 kilometers? • 5.9 s • How far can a person run in 15 minutes if he or she runs at an average speed of 16 km/hr? (HINT: Remember to convert minutes to hours.) • 4 km

  13. Speed – Advanced Practice • The speed of light is about 3.00 x 105km/s. It takes approximately 1.28 seconds for light reflected from the moon to reach Earth. What is the average distance from Earth to the moon? • 384000 km • The average distance from the sun to Pluto is approximately 6.10 x 109km. How long does it take light from the sun to reach Pluto? Use the speed of light from the previous question to help you. • 20000 s OR 333.3 min OR 5.6 h

  14. Distance-Time Graphs

  15. Velocity • What is the difference between speed and velocity? • Why is it called a speedometer and not velocitiometer? • Velocity is speed, but with a direction • It does not give you a direction, only a speed • Unless its combined with a compass

  16. Constant • If a car is driving 60 mph in a circle, does it have a constant velocity or speed? • Constant means it doesn’t change • The direction is changing, so it only has constant speed

  17. Constant If a car has a constant velocity of 30 m/s does it have a constant speed? If a car is going a constant speed of 25 m/s does it have a constant velocity? Yes, it will continue going 30 m/s. No, constant speed does not mean the constant direction

  18. Acceleration • Explain what acceleration means and identify which of the following are examples of acceleration.

  19. Motion How can we measure changes in velocity? • Acceleration – the rate at which velocity changes • Has direction (+ or - ) • Units: m/s2 • Acceleration formula • vf = final velocity • vi = initial velocity • t = time

  20. Motion A bike goes from rest to 20 m/s in 5 s, what is the acceleration? A runner going 10 m/s comes to a stop after 5 seconds, what was the acceleration? • 4 m/s2 • Positive = speed up • Same direction as v • Acceleration • -2 m/s2 • Negative = slow down • Opposite direction as v • Acceleration

  21. Motion What is the acceleration when you have a constant velocity? Any velocity minus itself is zero, so the acceleration would be zero

  22. Motion • If a truck at rest goes to 50 m/s in a northerly direction in 10 seconds, what is the truck’s: • Speed? • Velocity? • Acceleration? Speed = 50 m/s Velocity = 50 m/s north Acceleration = 5 m/s2 north

  23. Motion – More Practice • The cheetah, the fastest of land animals, can run a distance of 274 m in 8.65 s at its top speed. What is the cheetah’s top speed? • 31.7 m/s • In 1985, Matt Biondi set a record for the men’s 100 m freestyle even in swimming. It took him 49.17 s to swim the 100 m length of the pool. What was his speed? • 2.0 m/s • While drag racing out of our school parking lot, I time myself at a speed of 40 m/s, which was 7 s after starting. What was my acceleration during this time? • 5.7 m/s2 • A baseball is pitched with a speed of 35 m/s. How long does it take the ball to travel 18.4 m from the pitcher’s mound to home plate? • 0.53 s

  24. Acceleration Review

  25. BugattiVeyron vs. EuroFighter

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