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Motion and Light

Motion and Light. 2010-2011. Mav Mark 1/30/12. If Speed = Distance/time, What is the speed of a car That travels 120 miles in 2 hours?. Mav Mark 1/31/2012. Draw a distance/time graph and plot the following information.

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Motion and Light

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  1. Motion and Light 2010-2011

  2. Mav Mark 1/30/12 If Speed = Distance/time, What is the speed of a car That travels 120 miles in 2 hours?

  3. Mav Mark 1/31/2012 Draw a distance/time graph and plot the following information. A car takes 1 minute to travel 100km. It stops for thirty seconds, Then continues on for 1 minute as it goes another 1km.

  4. Mav Mark 2/1/12 What is the difference between the lithosphere and the asthenosphere?

  5. Mav Mark 2/2/12 • What forms at an Oceanic-Continental Convergent boundary? • What forms at a Continental-Continental Convergent boundary?

  6. Mav Mark 2/3/12 • What forms at an Oceanic-Oceanic Convergent boundary? • What forms at an Oceanic-Oceanic Divergent boundary? • What forms at a Continental-Continental Divergent boundary?

  7. Mav Mark 2/6/12 How can you tell the difference between distance/time graphs and Speed/time graphs?

  8. Mav Marks 2/7/12 • Draw a force diagram that shows balanced forces acting on an object. • Draw a force diagram showing unbalanced forces acting on an object, and tell which direction the object will move.

  9. Mav Mark 2/8/12 Write Newton’s three laws of motion and give an example that demonstrates Each.

  10. Mav Mark 2/9/12 • Draw and label the Electromagnetic Spectrum. • Draw and label a transverse mechanical wave.

  11. Mav Mark 2/10/12 Test Day Take out a Pencil and a Sheet of Paper Clear your Desk

  12. Motion • Motion is a change in position over time. • Motion depends on a reference point which is an object used for comparison with the object in motion. Stationary objects are good reference points. • Position is an object’s location in relation to a reference point.

  13. Reporting Motion • Qualitative: Describing motion • Fast or slow • Quantitative: measuring motion • Speed = Distance Time • Speed = 120 miles 2 hours • Speed = 60 miles/hour

  14. Speed vs Velocity • Velocity is speed plus direction. • Speed = 60 miles/hour • Velocity = 60 miles/hour north • Distance is how far the object traveled. • Time measures how long it took the object to travel the distance.

  15. d t v SPEED Speed is the distance that an object travels in a period of time. Units are meters and seconds However, sometimes km/hr is more sensible. A cyclist travels 25 km in ½ an hour. What is their speed - in kmhr-1 - in ms-1 = 25km/0.5hr = 50km/hr = 25000m/1800s = 13m/s

  16. 1.5 Distance (km) 1 0.5 1 2 3 Time (min) DISTANCE/TIME GRAPHS A car takes 1.5 minutes to travel 500m down a busy road. It stops at lights for 30 seconds, then continues on for 1 minute as it goes another 1km. Plot this on a distance/time graph. Δd = 1km Steepest section is fastest Using the distance/time graph: • What is the total distance traveled? 2. In what part of the trip is the car going the fastest? 3. What is the fastest speed? = 1.5 km Δt = 1min = part 3 v = Δd / Δt v = 1km/1min v = 1000m/60s v = 16m/s In a distance/time graph the slope of the line = the speed of the object.

  17. SPEED QUESTIONS What would these look like on a distance/time graph? 1. stopped 2. slow 3. fast 4. accelerating

  18. Δv a Δt ACCELERATION Acceleration is the change in speed in an object in a period of time. Units ms2 It takes a cyclist 20 secondsto go from a standing start to 14m/s. What is their acceleration? What is 14m/s in km/hr? a = Δv/Δt a = 14m/s / 20s a = 0.7ms2 = 14 × 60s × 60min  1000m = 50.4km/hr

  19. Acceleration • Acceleration is the rate of change in speed, direction, or both. • Riding your bike at 2 km/h, you slow down to 1 km/h, and then increase speed to 1.5 km/h. (Each time you are accelerating) • acceleration = velocity final - velocityinitial time

  20. SPEED/TIME GRAPHS Speed (m/s) 8 4 10 20 30 Time (sec) A runner travels at 4m/s for 10 seconds, then stops suddenly for 5 seconds, then accelerates for 5 seconds to get to 8m/s and continues for 10 seconds. Plot this on a speed/time graph. Using the speed/time graph: In what part of the trip is the runner going the fastest? What is the acceleration in part 4? = part 5 In a speed/time graph the slope of the line = the acceleration of the object. a = Δv/Δt a = 8m/s/5s a = 1.6ms-2

  21. ACCELERATION QUESTIONS What would these look like on a speed/time graph? 1. stopped 2. slow 3. fast 4. accelerating

  22. SPEED/TIME GRAPHS Speed (m/s) 8 4 10 20 30 Time (sec) In a speed/time graph the distance covered = the area under the graph. Part 2 Part 3 What distance is covered in part 1? What is the total distance covered? d = v × t d = 4m/s × 10s d = 40 m Part 4 Part 1 Part 1 = 40m Part 2 = 0m Part 3 = v × t ×  = 8m/s × 5s ×  = 20m Part 4 = v × t = 8m/s × 10 s = 80m Total = 40 + 20 + 80 =140m

  23. Motion on Earth • Theory of Plate Tectonics states that Earth’s plates move slowly in various directions through convection energy transfer in the mantle. (some push away; some push together) • Tectonic plates are large pieces of the lithosphere that are in constant motion. • Some move cm each year; others just mm • Distance=5cm/year x 1000 years=5000cm (50m)

  24. Motion on Earth • Lithosphere is the rocky outer shell of Earth that includes the crust and upper mantle. (brittle and rigid) more solid • Continental Crust: composed of sedimentary, igenous, and metamorphic rocks and make up the continents • Oceanic Crust: more dense, thinner mafic rock layer that makes up ocean basins • The asthenosphere lies just below the lithosphere. It is much hotter with a low density and very ductile. (plastic and flowing) more liquid

  25. Motion on Earth • Plate Boundary: Region where two tectonic plates meet • Transform (fault) boundary: Plates slide side by side. • Convergent boundary: Plates move towards each other. • Divergent boundary: Plates move away from each other.

  26. Oceanic-Continental Convergent: Oceanic plate is more dense and subducts the continental plate creating an ocean trench and a chain of volcanoes.

  27. Continental-Continental Convergent: The two plates collide creating a mountain range.

  28. Oceanic-Oceanic Convergent: collide to create volcanoes and islands in between.

  29. Oceanic-Oceanic Divergent: Forms mid-oceanic ridges leading to underwater volcanoes that give rise to volcanic islands.

  30. Continental-Continental Divergent: Produce rift valleys eventually creating oceanic plates.

  31. Motion on Earth

  32. FORCES Forces are pushes or pulls (a combination is a twist).   Objects are stationary when forces are balanced gravity is always acting but we don’t keep falling due to a support force Forces can be measured using a Newton meter.

  33. BALANCED FORCES An unbalanced force causes changes to objects motion (speed or direction), or shape. If a force acts on a stationary object and causes motion, the object has gained kinetic (movement) energy. Friction will stop the object moving. Types of force: Gravity Friction – the force that opposes motion Magnetism Tension – the force in rope, etc Electrostatic Support Lift – in the air (planes/birds) Bouyancy – in the water

  34. FORCE PAIRS Forces act in pairs (e.g. thrust and friction, gravity and support). Force diagrams show the forces acting on an object and whether they are balanced or unbalanced.

  35. Force pairs What are the missing terms? Buoyancy Drag Thrust Weight

  36. Newton’s 1st Law of Motion • An object at rest will remain at rest unless acted on by an unbalanced force. An object in motion continues in motion with the same speed and in the same direction unless acted upon by an unbalanced force.

  37. Newton’s 2nd Law of Motion • Acceleration is produced when a force acts on a mass. The greater the mass (of the object being accelerated) the greater the amount of force needed (to accelerate the object).

  38. Newton’s 2nd Law of Motion • EX: Mike's car, which weighs 1,000 kg, is out of gas. Mike is trying to push the car to a gas station, and he makes the car accelerate at 0.05 m/s/s. Using Newton's Second Law, compute how much force Mike is applying to the car.

  39. Small constant force FORCE AND MOTION What happens when you apply a small constant force to a trolley and time it over a set distance? Set distance The trolley should accelerate because… An unbalanced force causes acceleration.

  40. Small constant force FORCE AND MOTION What happens when you apply a small constant force to a trolley carrying a 1kg mass and time it over a set distance? 1Kg Set distance The trolley should accelerate but slower than previously because… The larger the mass the slower the acceleration

  41. 150N 800N FORCES AND ACCELERATION Given the formula F = ma try the following questions. 1. What are the names and units of F, m and a? 2. Complete the table…. 3. The rider and cycle are 150kg: a. What is the Nett force? b. What is the cyclist’s acceleration? 4. A bike accelerates at 10ms-2 using a force of 6000N. The rider is 70kg. What is the mass of the bike?

  42. WEIGHT FORCE Weight is a force. It is therefore measured in… An object’s weight depends on two things… Newtons (N) Gravity • varies depending where you are • 10ms-2 or 10N/Kg on Earth Mass • does not vary • measured in Kg • A man with mass of 75Kg on earth weighs 750N BUT on the moon he weighs 125N

  43. The Source of Friction • Friction- A force that opposes motion between 2 surfaces that are touching • Friction occurs because the surface of any object is rough. • The amount of friction depends upon many factors like: • Roughness of the surfaces • Force pushing the surfaces together

  44. FRICTION  Friction can be reduced by… lubrication, streamlining (aerodynamics), slowing down, smoothing surfaces

  45. Newton’s 3rd Law of Motion • For every action there is an equal and opposite re-action. • Ex: Rocket Launching, Walking

  46. Waves • Waves: a disturbance that travels through a medium from one location to another often transferring energy • Transverse: causes vibration in the medium in a perpendicular direction to its own motion. • Example: Light, Electromagnetic spectrum • Longitudinal: have vibrations along or parallel to their direction of travel. • Example: Sound

  47. Waves • Wavelength: the distance between adjacent crests, measured in meters. • Period: the time it takes for one complete wave to pass a given point, measured in seconds. • Frequency: the number of complete waves that pass a point in one second, measured in inverse seconds, or Hertz (Hz). • As frequency increases, Wavelength decreases

  48. Waves • Refraction: the change in direction of a wave due to a change in its speed. • Wave speed varies in different media. • Sound waves travel faster in water than air. (Sonar) • Light waves travel faster in air than water.

  49. Electromagnetic Spectrum • Visible Light: ROY G BIV (Red has longer wavelength.) • The range of all possible electromagnetic radiation.

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