1. Vector Components Topic – Physics 2a Key words
Component force, horizontal, vertical, right angled triangle,

2. Force as a vector
Forces that act directly on a body are called contact forces as the body will only experience the force when in contact
Forces that act on a body from a distance are called non-contact forces

3. Examples of contact forces
Bouncing ball
Adhesion – sellotape and paper
Cohesion – attraction between particles of the same material – water droplets
Surface tension –across molecules of a liquid
Any force that occurs when 2 or more bodies touch

4. Forces make objects ….. Change shape Change speed
Change direction of motion

5. Forces Measured in Newtons (N)
A force of 1N is the force required to hold 100g of mass against the force of gravity

6. Force as a vector quantity
Magnitude and direction of a force is needed if effect of force is to be determined
Force is therefore a VECTOR quantity = magntude + direction.
Force symbol = F

7. Drawing forces A vector is represented by a line segment
4N left
2F = 8N left
½ F = 2N left
-F = 4N right
A vector is represented by a line segment
Line is drawn to a specific scale
If the force is doubled = 2F
Half the force = ½ F
Multiplying the forces by a number (scalar) affects only the magnitude of force not the direction.
When a vector is multiplied by a negative number the sign is interpreted by reversing the direction of the vector

8. Direction conventions
A full circle bearing describes north as zero degrees true
Written as 0oT
90oT = 90 degres clockwise from north
180oT = due south
270oT = due west
45oT = NE or N45E
315oT = NW or N45W

9. convert
Convert quadrant bearing S50W to a full circle bearing in To

10. convert Convert quadrant bearing S50W to a full circle bearing in To
Answer:
South is 180
= 50 further west
= 230
230oT

11. Notes – Vector techniques Forces
Copy summary notes 3.2 vector techniques page 96

12. Vector techniques
If only one force acts upon a body at rest the body has no alternative than to move in the direction of that force – e.g. golf ball being hit by a golf club
If more than one force acts on a body the body behaves as if only one force is acting – the vector sum
This is called the resultant or the net force €F

13. Adding vectors
Because force is a vector adding numbers must take direction into account
2N + 3N in the same direction would be 5N in that direction.
However 2N left + 3N right = 1N right
When at an angle to each other the magntude will be somewhere between 1 and 5

14. Adding vectors graphically
A vector diagram is drawn
Either to scale = resultant vector can be measured Or
Sketched and use mathematical equations

15. Adding vectors graphically = page 96
Steps:
Draw ref grid of direction NSEW
Determine scale
Write vector equation – EF (net)
Draw first vector to scale
From head of arrow draw second vector to be added
Resultant vector will be the direct line from tail of first vector to head of second vector
Magnitude will be the length
Direction is direction of the vector

16. Vector components – pg 94
If a hockey puck is hit at a force 100N north 30o west
Some of this is a northerly component
Some is a westerly component
To determine component forces you need to construct a right angled triangle around the force vector.
Either trigonometry or scale diagram can be used to calculate the components.
Fh= sinθ
Fv= cosθ
F 100N θ
θ = 30o
1 cm represents 25N
N = 87N
W = 50N

17. Example – pg 95 Foot pushes down and backwards when walking
400N backwards and 600N down
What is the total force applied by her foot?
F = FH + FV
draw vector diagram
F =√ FH2 + FV2
F =√
F = 721 N
F ?
Fv= cosθ
600N θ
Fh= sinθ
400N
θ= tan-1 (opp/adj)
θ= tan-1 (600/400)
tan-1= 1.5 = 56o

18. Question -pg 95
A skier is pulled up a hill at a force of 1500N at an angle of 30o.
Determine the horizontal and vertical force?
F 1800 = FH + FV
draw vector diagram
Fv = Fcosθ= 1500cos30o = _________
Fh= Fsinθ = 1500sin30o=
_______
F 1800
Fv= cosθ ? θ
Fh= sinθ ?

19. Question – try this one
A skier is pulled up a hill at a force of 1800N at an angle of 40o.
Determine the horizontal and vertical force?
F 1800 = FH + FV
draw vector diagram
Fv = Fcosθ= 1800cos40o = _________
Fh= Fsinθ = 1800sin40o=
_______
F 1800
Fv= cosθ ? θ
Fh= sinθ ?