1 / 88

Unit : 2D Motion Lesson : Distance Vs Displacement

Unit : 2D Motion Lesson : Distance Vs Displacement. Year 10. /. /. Brainstorming Activity. Motion?. Motion is the change in position of an object with respect to time. Motion is typically described in terms of velocity, acceleration, displacement and time. Motion Terms. Distance

gili
Télécharger la présentation

Unit : 2D Motion Lesson : Distance Vs Displacement

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Unit : 2D MotionLesson: Distance Vs Displacement Year 10 / /

  2. Brainstorming Activity

  3. Motion? • Motion is the change in position of an object with respect to time. • Motion is typically described in terms of velocity, acceleration, displacement and time.

  4. Motion Terms • Distance • Displacement • Speed • Velocity • Rate • Acceleration • momentum

  5. Distance Vs Displacement Any Volunteer please ?

  6. Displacement v Distance Distance • is the total length of the path of motion • Scalar quantity- has size and no direction. Displacement • is the linear distance between the initial and final point of an object • Vector quantity- has both size and direction

  7. Vector or Scalar? • 5 m • 30 m/sec, East • 5 m, North • 20 degrees Celsius • e. 256 bytes • f. 4000 Calories

  8. Calculations: Example 1 home (starting point) school (end point) Distance= 1.2+2+2+2+1.2 Displacement= 7.4m = 8.4m south east

  9. Example 2: A 8m D 4m 4m B 8m C Krusty the clown travels from D to A, A to B, B to C and C to D. Distance? Displacement?

  10. Speed vs. Velocity Speed Velocity • Measure of how quickly something moves • Scalar quantity • Speed can be measured in different units. E.g . m/s, km/h, km/s, miles per hour. Conversion: • speed in 3.6 speed in km/h in m/s • Speed 3.6 speed in m/s in km/h • The rate at which an object changes its position. • Vector quantity • The direction of the velocity is simply the same as the direction that an object is moving. • E.g airplane moving towards the west with a speed of 300 mi/hr has a velocity of 300 mi/hr, west • Average velocity= Position/time = displacement/time

  11. Example: 1. Convert 3m/s into km/h. Solution 3 m/s = 3 × 3.6 km/h = 10.8 km/h 2. Convert 54km/h into m/s. Solution 54 km/h = 54 ÷ 3.6 m/s = 15 m/s (worksheet 1- unit conversion, velocity and displacement)

  12. Question 1 • Convert the following into the standard units (metres and seconds): (a) 3 km (b) 37 cm (C) 3mins

  13. Solution • 3000m • 0.37m • 180seconds

  14. QUESTION 2 • Convert the following times into the units in brackets: (a) 300 s (min) (b) 9 hours (min) (c) 750 min (hours)

  15. Solution • 5mins • 540mins • 12.5hrs

  16. Question 3 • A small car can top speed at 180 km/h. Write this in SI units (m/s). • Convert 3m/s into km/h

  17. Solution • Convert km/h into m/s by 3.6 Therefore: 180/3.6 = 50m/s • Convert m/s into km/h by 3.6= • 3 × 3.6 km/h = 10.8 km/h

  18. 2nd power point slide

  19. QUESTION 4 • A taxi drives 360km in 4 hours. (a) What is the average speed? (b) How long will it take to drive 540km at the same speed?

  20. Solution • Average Speed = Total Distance (km) Total Time (hr) = 360/4 = 90km/hr Time taken = Distance Speed = 540/90 = 6hrs

  21. Question 5 Trinh rides her bike with a constant speed of 5 m/s. It takes her 3 minutes to get to the milk bar. Calculate how far away it is.

  22. Solution First, convert the time she took into seconds in order to state the answer in metres. t = 3 × 60 = 180 s Trinh has travelled: d = v × t = 5 × 180 = 900 m • The milk bar is 900 m away.

  23. Question 6 Theo spent 8 hours travelling 400 km from his home in Bundaberg to visit his sister in Toowoomba. Calculate Theo’s average speed for the journey.

  24. Solution Speed (km/h) = distance (km) time (hr) = 400/8 = 50km/h

  25. Calculating Speed & distance average speed = total distance travelled (m) total time taken (s) or v = d/t (m/s)

  26. Instantaneous Speed • Speed at a particular instant. • Why do you think instantaneous speed is important??

  27. Velocity • The rate at which displacement changes. • Vector quantity • Simply a speed with dirction • Average velocity= Change inPosition = Displacement Time Time

  28. Measuring Speed using ticker timer

  29. Describing Motion Ticker Tape – dots made on a tape at 50 dots per second

  30. Describing Motion • The spacing of the dots on a ticker tape tells you what type of motion it is. Each new dot represents 0.02 seconds has passed • The distance between the dots is the distance travelled in 0.02 s

  31. Describing Motion

  32. Deceleration on a ticker timer tape?

  33. Describing Motions with Diagrams

  34. Graphing motion • Distance-time graph time is always placed • Displacement-time graph on the horizontal axis. • Speed-time graph

  35. Distance-Time Graph- shows how far an object travels as time progresses. fast slow not moving d d d t t t • The steeper the gradient, the faster the object is moving. • The slope or gradient of a distance-time graph is equivalent to the object’s average speed over a time interval choose two points to calculate the gradient and use the formula RISE/RUN

  36. What is the speed of the object between points A and B? Example: • Choose two points to calculate the gradient • Gradient=rise/run • the object has moved 60m (70 – 10) B 70 60 50 40 • it took 3s to move this distance (6 – 3) distance (m) 30 20 • speed = distance/time A 10 = 60/3 0 0 1 2 3 4 5 6 7 8 9 = 20m/s time (s)

  37. Question • Below is a distance vs. time graph for 3 runners. Who is the fastest?

  38. Distance v Time Graph the motion of the car. Describe the motion? x x x x x

  39. Distance v Time Graph the motion of the car. Describe the motion?

  40. Distance v Time

  41. Speed-time graph • Speed – time graph are also known as velocity-time graph • A speed- time graph shows how an object’s speed changes over time • The area below a speed time graph is the distance the object has travelled up to a given point

  42. This graph shows increasing speed. The moving object is accelerating This graph shows decreasing speed. The moving object is decelerating A straight horizontal line on a speed-time graph means that speed is constant. It is not changing over time. A straight line does not mean that the object is not moving

  43. What about comparing two moving objects at the same time?

  44. Answer: • Both the dashed and solid line show increasing speed. • Both lines reach the same top speed, but the solid one takes longer. • The dashed line shows a greater acceleration.

  45. Graphing speed power point- car example 3rd slide

  46. Displacement – time graph The displacement – time graph shows the journey of a woman going to a corner shop and back. Calculate each of the following. (a) Her total distance travelled. (b) Her final displacement. (a) 60 + 60 = 120m (b) 0

  47. Distance v Time Changing velocity slow then fast Constant velocity Changing velocity is acceleration Changing velocity fast then slow Constant velocity - less

  48. a = (v - u ) t vave = s t Motion Formulas vave = (u + v ) 2 s = v.t - ½ a.t2 s = ut + ½ a t2 v2 = u2 + 2as p = m . v

More Related