1. Motion and Its Applications
UNIT ONE

2. Motion Part of the everyday physical world
We learn to walk, run and drive without really understanding the physics of motion
We have an intuitive idea of motion and its effects and causes

3. Unit 1: Motion and Its Applications
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Motion
Movement of an object from one place to another, as measured by an observer
Two objects are in motion with each other if the straight-line segment between them changes in:
Length
Direction
Or both

4. Are the carts in motion with reference to each other? Explain.
Two golf carts are travelling at the same speed in the same direction along a straight level path.
Are the carts in motion with reference to each other? Explain.
8/6/2018

5. Uniform Motion Non-Uniform Motion
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Uniform Motion
movement at a constant speed in a constant direction (rare!!)
Non-Uniform Motion
Movement that involves changes in speed or direction or both

6. Uniform or Non-Uniform?
A) A rubber stopper is dropped from your raised hand to the floor.
B) A car is travelling at a steady rate of 85 km/h
C) A motorcycle rider applies the brakes to come to a stop
8/6/2018

7. Physical Quantities Two Types: Scalar Quantities
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Two Types:
Scalar Quantities
Only have a size and a unit .
7 days, 2 m. 3 kg
Vector Quantities
Have a size, unit, and a direction.
3 m [E] , 15 N [S]
**note the square brackets

8. Vector or Scalar? 50 km/h 6 km/h [N] 2000 kg/m3 6 centuries
20 m/s [down]
800 kg
23 m

9. Distance, Position and Displacement
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Distance, Position and Displacement
Distance
is the total length of the path travelled by an object
Represented by ∆d (∆ means ‘interval of’)

10. Distance
For example, if you walk directly from home to the school in a straight line, you will travel a distance of 500 m
If you walk from the school to the library and then return home, you will travel 1900 m (700 m m)

11. Position Is the location of an object relative to a reference point
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Position
Is the location of an object relative to a reference point
It is a vector quantity, so direction must be indicated
Symbol =

12. Position
For example, if home is your reference point, the position of the school is 500 m [E]
Note: the magnitude of the position is the same as the straight-line distance (500 m) from home to school, but the position also includes the direction

13. Displacement
Refers to the change in position of an object from its initial position to its final position
It is a vector quantity
Unlike position, displacement does not require a reference point
Symbol = ∆

14. Displacement
For example. If you walk directly from home to school your displacement is 500 m [E] (500 m[E] – 0)
If you then walk from the school to the library and then return home, your total displacement will be 0 (500 m[E] m[E] m[W]
Recall: displacement is the CHANGE in position

15. Practice
What is your (i) distance and (ii) displacement if a) you walk from the school to home and then to the library?
d= 1700 m; = 700 m[E]
b) you walk from home to the school and then to the mall? d = 2000 m; = = 1000 m[W]
A dog, practicing for her agility competition, leaves her trainer and runs 80 m due west to pick up a ball. She then carries the ball 27 m due east and drops it into a bucket. What is the dog’s total displacement?
= 53 m[W]

16. Check Your Understanding
Textbook: pg 13, #1-4 (photocopy)

17. Adding or Subtracting Vectors in a Straight Line

18. Adding/Subtracting Vectors in a Straight Line
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Adding/Subtracting Vectors in a Straight Line
A vector quantity is represented on a diagram by a line segment with an arrow at one end to indicate direction
We can add vectors together in two ways:
1. Graphically
- Draw both vectors to the same scale and connect them from tip to tail
- Draw a vector from the tail of the first to the head of the second vector, label it R (from where you started, to where you ended up)
- Measure the length of the resulting vector
Tail
Tip

19. Eg. 6 km[E] plus 5 km[W] 1 cm = 1 km
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Eg. 6 km[E] plus 5 km[W] cm = 1 km
The resultant vector is 1 km[E] (measured)

20. - assign each direction as positive or negative
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2. Algebraically:
- assign each direction as positive or negative
Eg. 6 km[E] plus 5 km[W]
Let [W] be negative and [E] be positive
Displacement = 6 + (-5)
= +1
= 1 km[E]

21. Try these…. Solve the following graphically and algebraically
3 km[E], then 15 km[W]
11 km[E], then 15 km[E], then 10 km[E]
1 km[W], then 2 km[E], then 2 km[W]
5 km[S], then 2 km[N], then 3 km[S]

22. Text pg. 13, #5 and 6 (photocopy)