1. Chapter 4
Motion

2. 4.1
Position, Speed, velocity

3. Vocabulary
Position – a variable that tells location relative to origin
Origin – a place where the position has been given a value of zero
Speed – how quickly an object moves
Instantaneous Speed – the actual speed of a moving object at any moment

4. The Position Variable Position Vs Distance
The distance of the car from the origin is 50 cm
The position of the car is 50 cm to the right of the origin
You cannot have negative distance.

5. Speed
If you drive 120 miles (the distance) and it takes you 2 hours (the time) your speed is 60 miles per hour
(120 mi/2 hr = 60 mph)
Think about a road trip, your average speed might be 70 mph, but maybe there was traffic (speed = 15 mph) or maybe you were speeding at one point (speed = 80 mph). This is the difference between average speed and instantaneous speed.

6. Speed
How far will you go if you drive for 2 hours at a speed of 100 km/h?
You travel at an average speed of 20 km/h in a straight line to get to your grandmother’s house. It takes you 3 hours to get to her house. How far away is her how from where you started?
What is the speed of a snake that moves 20 meters in 5 seconds?
A train is moving at a speed of 50 km/h. How many hours will it take the train to travel 600 kilometers?

7. Vocabulary Vector – a variable that gives direction information
Velocity - a variable that tells you both speed and direction

8. Vectors and Velocity
Position is an example of a vector – it tells you direction and an amount
Moving forward is represented with a positive, moving backward is represented with a negative
Velocity is speed with direction
Velocity is a vector, speed is not

9. Maps and Coordinates
One way to describe is to use a coordinate grid (think north and south as the y-axis and east and west as the x-axis)
A graph that displays these axis is called a map
Suppose you run easy for 10 seconds at a speed
of 2 m/s. Then you turn and run south at the
same speed for 10 more seconds. Where are you
compared with where you started?

10. Problems: Velocity
A train travels at 100 km/h heading east to reach a town in 4 hours. The train then reverses and heads west at 50 km/h for 4 hours. What is the train’s position now?

11. Demonstrate Motion and Shoot the Monkey Gizmo
Classwork
P 86 # 1- 8
Demonstrate Motion and Shoot the Monkey Gizmo

12. 4.2
Motion Graphs

13. Vocabulary Constant Speed – speed that stays the same
Slope – is the ratio of the rise (vertical change) to the run (horizontal change)

14. Position vs Time Graph
This is a position vs time data because it tells you the runner’s position at different points in time. What is the runner’s constant speed?

18. Graphs show relationships between variables
The image to the left shows you the relationship between the angle of the racetrack and the speed of the car
The graphs above show a weak or no relationship between variables.

19. Speed vs Time Graph The graphs below show two runners in a race:
What similarities and differences are shown in the two graphs?
How can you tell the speed from the first graph?
How can you tell the distance from the second graph?
Speed = distance/time
1st graph example of speed: the blue runner ran 100 m in 20 sec so the speed is 5 m/s
2nd graph example of distance: the blue runner ran at a speed of 5 m/s for 60 sec so 5 m/s = d/60s 60*5 = 300 m

20. Demonstrate Distance- Time Graph Gizmo
Classwork
P 91 # 1- 9
Demonstrate Distance- Time Graph Gizmo

21. 4.3
Acceleration

22. Vocabulary Acceleration – the rate at which velocity changes
Free Fall – accelerated motion that happens when an object falls with only the force of gravity acting on it
Acceleration Due to Gravity – the value of 9.8 m/s2, which is the acceleration in free fall at Earth’s surface, usually represented by a small letter g
Projectile – an object moving through space and affected only by gravity

23. Acceleration
Think about pressing the gas pedal, the car speed increases
If you press the brakes, the car slows down
Acceleration describes changes in speed or velocity

24. Acceleration
Think about going up bicycling down a hill, at the top you move slowly but towards the bottom you are move must faster as you accelerate
The acceleration depends on the steepness of the hill

25. Speed and Acceleration
Acceleration describes how quickly speed changes

26. Speed and Acceleration
A sailboat moves at 1 m/s. A strong wind increases its speed to 4 m/s in 3 seconds. Calculate the acceleration.
Calculate the acceleration of an airplane that starts at rest and reaches a speed of 45 m/s in 9 seconds.
Calculate the acceleration of a car that slows from 50 m/s to 30 m/s in 10 seconds.

27. Acceleration Motion Graphs
Positive Acceleration shows things getting faster
Negative Acceleration shows things getting slower (Deceleration)
It is curved because it is increasing speed each second

28. Free Fall
Think of a ball, as soon as it leaves your hand it is in free fall because essentially the only force acting on it is gravity
If the air friction is ignored the force of gravity will increase the speed 9.8 m/s every second.

29. Free Fall
Constant acceleration mean’s an object’s speed changes by the same amount each second

30. Acceleration and Direction
If an object’s acceleration is zero the object can only move at a constant speed in a straight line (or be stopped)
Acceleration occurs whenever there is a change in speed, direction, or both.

31. Curved Motion Curved motion is caused by sideways accelerations
This causes the velocity to change direction, which results in turning, creating curved motion
A soccer ball is an example of a projectile, moving under the influence of gravity

32. Classwork
P 99 #2-11