1. Motion and Speed

2. Displacement and Velocity

3. Motion and Position Motion occurs when an object changes its position.
In order to tell if something has moved, you need a reference point.
An object is in motion if it changes position relative to a reference point.

4. Point A --------> Point B
Frame of Reference
- In order to measure the distance of an object we must use a frame of reference.
Point A > Point B
- These are usually distinct points on the Earth's surface or distinguishing points in the sky.

5. Distance How far something moves is distance.
Distance is measured in centimeters, meters or kilometers.
One km is equal to .6 miles or 1000 meters.

6. Distance is a scalar quantity and tells you only the magnitude (number sum only) of a path taken.

7. Displacement
Displacement is the distance AND direction of an object’s change in position from starting point.

8. Displacement is the shortest distance between the starting point and the end point.

9. Distance vs. Displacement
You drive the path, and your odometer goes up by 8 miles (your distance).
Your displacement is the shorter directed distance from start to stop (yellow arrow).
start
stop

10. Speed is the distance traveled
by a moving object over
a period of time

11. Constant speed
A moving object that doesn’t change it’s speed travels at constant speed
Constant speed means equal distances are covered in an equal amount of time

12. Calculating Speed Speed = Distance Time Distance = speed x time
If a runner travels 100 m in 10 seconds what was his average speed?

13. Calculating Speed Speed is distance divided by time.
Distance is meters and time is seconds.
Other units can be used, such as kph or mph.

14. SPEED
Speed is the distance that an object travels in a period of time. d t v
Units are meters and seconds (and therefore meters per second). However, sometimes km/hr is more sensible.
A cyclist travels 25 km in ½ an hour.
What is their speed - in kph
- in mps
Meters per second
= ms = m/s = ms-1
H/O activity 18.2 Running speeds
H/O Bubble gum champ
= 25km/0.5hr = 50km/hr
= 25000m/1800s = 14m/s

15. Velocity is speed in
a given direction

16. instantaneous velocity - the velocity that something has at any one instance
(The terms instantaneous speed and avg. speed may also be used)

17. The average velocity for a trip might be 53 miles/hour.
However, during this trip your instantaneous speed might have been 0 miles/hour at a stoplight or 70 miles/hour on the open road.

18. Really…you think YOU are FAST?

19. Speed Records Vehicles Conventional passenger train… 456 mph
Hydroplane…317 mph
Land car…763 mph
NASCAR … 213 mph…Bill Elliot!

20. Birds Peregrine falcon…217 mph (dive) Hummingbird…62 mph
Ostrich …40 mph

21. Fish Fastest man…5mph Great white burst…15 mph
Mako Shark…burst 60 mph…you’re dinner.
Killer whale…25 mph … that’s why they call them killer!
Dolphin…35 mph
Sailfish…68 mph

22. Other sea creatures Shrimp…1.9 mph Sea turtle…22 mph Crab…4.7 mph
Octopus 25 mph…sad but faster than you!

23. Mammals Cheetah…70 mph Pronghorn Antelope…65 mph Lion…50 mph
Tiger…50 mph

24. Mammals cont. Grey wolf…45 mph… Racehorse…40 Grizzly bear…30 mph
Wart hog…30 mph

25. Getting’ slower! Dog …40 mph Cat …30 mph Elephant…25 mph Man…23 mph
Mouse…8 mph

26. You still better run! Black mambo snake…20 mph Bee…11 mph
Cockroach…3.4 mph
Spider…1.17 mph
Snail…0.03 mph…

27. Motion with Constant Speed
Motion or speed can change or stay constant.
With constant speed, speed does not change.

28. Speed
Speed can
Change
Be average
Be instantaneous

29. Average vs Instantaneous
Average speed is the total distance traveled divided by the total time of travel.
S = d/t
Instantaneous speed is the speed at a given point in time.
Use a speedometer.
If something is speeding up or slowing down instantaneous speed is changing.

30. Calculations
Sound travels at a speed of 330 m/s. If a lightning bolt strikes the ground 1 km away from you, how long will it take the sound of thunder to get to you?

31. S = d/t so t = d/s
t = 1 km/330 m/s = 1000m/330 m/s = 3.03 s

32. Graphing Motion
A distance-time graph displays motion of an object over time.
So, what is going on?

33. Plotting a distance–time graph
Distance is on the vertical axis
Time is on the horizontal axis
Appropriate time and distance intervals are added
Data is plotted
Line is drawn

34. 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.
Distance
(km)
0.5 1
1.5
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
EXPT H/O speed challenge or Gather own data from 100m and draw some graphs
Time (min) 1 2 3
v = Δd / Δt
v = 1km/1min
v = 1000m/60s
v = 16.66m/s
In a distance/time graph the slope of the line = the speed of the object.

35. Can you tell what this vehicle is doing?
The car went 10 m/s for 150 seconds (A), then the car accelerated until it got to (B) when it was finally going 30 m/s.  The car then went 30 m/s for 50 seconds (C).  Finally, the car decelerated from 30 m/s to 5 m/s for the final 50 seconds of its journey (D).

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

37. SPEED/TIME GRAPHS
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.
Speed
(m/s) 4 8
Using the speed/time graph:
In what part of the trip is the runner going the fastest?
Time (sec) 10 20 30
Part 5 = 8m/s
= part 5
In a speed/time graph the slope of the line = the acceleration of the object.

38. Velocity Part 2

39. Velocity Velocity is the speed and direction of movement.
Speed in a given direction is velocity.
For example, a storm is moving east at 25 miles per hour, is the velocity of the storm.

40. Velocity
Because velocity depends on speed and direction, the velocity of an object can change even if the speed, direction or both change.
Think NASCAR.

41. Resultant Velocity
Resultant velocity is when you combine two velocities.

42. Resultant Velocity
When you combine two velocities that are in the same direction, you add them together to get the resultant velocity.
When you combine two velocities that are in opposite directions, subtract the smaller velocity from the larger velocity. The resultant velocity is in the direction of the larger velocity.

43. If the plane is traveling at a velocity of 100 km/hr with respect to the air, and if the tailwind velocity is 25 km/hr, then what is the velocity of the plane relative to an observer on the ground below?
Science Rules!

45. Understand???

46. Now…
Suppose a plane traveling with a velocity of 100 km/hr with respect to the air meets a headwind with a velocity of 25 km/hr. In this case, the resultant velocity would be 75 km/hr.

47. Get it?

48. Acceleration Acceleration is the rate of change in velocity.
When velocity changes, acceleration changes.

50. Acceleration cont… Remember, velocity is involves speed and direction.
Sooooo, if speed or direction change, or both actually, acceleration occurs.
Acceleration is not just speeding up.

51. Acceleration
When a motorcycle changes direction, its velocity changes too.

52. Positive acceleration
Positive acceleration is an increase in speed.

53. Negative acceleration
Slowing down is negative acceleration.

54. Changing direction
Changing direction is also acceleration because the moving object is changing velocity.

55. Calculating Acceleration
change in velocity
Acceleration = time
Subtract the initial velocity from the final velocity to get change in velocity.
Vi stands for initial velocity and vf stands for final velocity.

56. units Acceleration is a unit of velocity divided by a unit of time.
The SI unit for velocity is meters per second (m/s) and the SI for time is seconds (s).
So, the unit for acceleration is meters /second/second which is written as m/s2 and is read as meters per second squared.

57. ACCELERATION
Acceleration is the change in velocity in an object in a period of time.
Δ v a
Δ t
Units ms/s or ms2
It takes a cyclist 20 seconds to go from a standing start to 14m/s.
What is the acceleration?
What is 14m/s in km/hr?
a = v  t
a = m/s  s
a = m/s/s
=m/s2
= ms-2
H/O foot on accelerator or workbook exercises
a = Δv/Δt a = 14m/s / 20s a = 0.7ms-2
= 14 × 60s × 60min  1000m
= 50.4km/hr

58. Calculating positive acceleration
A jet plane starts from rest at the end of the runway and reaches a speed of 80 m/s in 20 s. What is the jet’s acceleration?
(vf – vi) ( 80 m/s – 0 m/s)
a = t = s = 4 m/s/s

59. Calculating negative acceleration
A skateboarder moving at 3 m/s comes to stop in 2 s. What is the acceleration?
( vf – vi) (0 m/s – 3 m/s)
a = t = s = m/s2
Since acceleration is a negative number, it is negative acceleration and the object is slowing down.

60. Forces