Topic 4.1 : Forces

Topic 4.1 : Forces
Learning goals:
  • I can explain what a force is and can identify different types of
    forces.
  • I can calculate the gravitational force acting on an object.
  • I can draw arrows on a force diagram,
                 with the correct point of
    application, magnitude and direction. 
  • I can calculate the resultant force of forces going
                 in the same
    direction or opposite directions of each other. 
  • VWO ONLY - I can calculate the resultant force
1 / 25
next
Slide 1: Slide
ScienceMiddelbare schoolhavoLeerjaar 2

This lesson contains 25 slides, with interactive quizzes and text slides.

Items in this lesson

Topic 4.1 : Forces
Learning goals:
  • I can explain what a force is and can identify different types of
    forces.
  • I can calculate the gravitational force acting on an object.
  • I can draw arrows on a force diagram,
                 with the correct point of
    application, magnitude and direction. 
  • I can calculate the resultant force of forces going
                 in the same
    direction or opposite directions of each other. 
  • VWO ONLY - I can calculate the resultant force

Slide 1 - Slide

Topic 4.1 : Forces
Forces are all around us, You can’t see them !
You can only see their effect

Object changes shape
Object starts to move
Object changes speed
Direction of object changes

Slide 2 - Slide

Topic 4.1 : Forces
Object changes shape

Slide 3 - Slide

Topic 4.1 : Forces
Object starts to move

Slide 4 - Slide

Topic 4.1 : Forces
Object changes speed

Slide 5 - Slide

Topic 4.1 : Forces
Object changes direction

Slide 6 - Slide

Topic 3.1: Forces
There are many types of forces
Types of forces
Unit
Also known as
Gravity
Fg
Applied force
Fa
muscle force
Air resistance
Fair
drag
Friction
Ff
Tension force
Ft
Spring force
Fs
elastic force
Normal force
Fn
support force
Topic 4.1: 
Forces

Slide 7 - Slide

Air resistance force
Gravity force
Spring force
magnetic force

Normal Force
Tension Force
applied force
Friction force

Slide 8 - Drag question

Topic 4.1: Forces
Force (F)
Measured in Newtons (N)

The force needed to lift 1 kg = 9.8 N on earth
On the moon the force needed is only 1.6 N
The mass is the same
Gravitational force is different

Slide 9 - Slide

Topic 4.1: Forces
Formula for calculating Gravity force


Fg is the gravitational force in [N]
m is the mass in [kg]
9.8 is the gravitational constant on earth in N / kg or 
Fg = m x 9.8
m / s2

Slide 10 - Slide

Topic 4.1: Forces
Example: 
The mass of Peter is 76 kg. What is his gravitational force, Fg?

Fg                        = m x 9.8 
Fg = 76 [kg] x 9.8 [N/kg]
Fg                      = 744.8 [N]



Slide 11 - Slide

The mass of Mohamed is 45 kg. What is his gravitational force, Fg
A
350 N
B
45 N
C
441 N
D
882 N

Slide 12 - Quiz

The gravitational force of my cat is 34.3N What is her mass?
A
34,3 kg
B
3,5 kg
C
336 kg
D
24,5 kg

Slide 13 - Quiz

Topic 4.1 : Forces
Forces are represented by an arrow

It has three things:

1. point of application (origin of force)
2. direction
3. magnitude (the longer the arrow, the bigger the force)

Slide 14 - Slide

Topic 4.1: Forces
1. point of origin: 
Centre of mass

2. Direction: 
downward

3. Magnitude:
depending on scale


Slide 15 - Slide

Name types of forces

Slide 16 - Mind map

A forces is drawn with a length of 4 cm
The scale is 1 cm = 30 N
What is the magnitude of the force drawn?
A
60 N
B
30 N
C
120 N
D
7,5 N

Slide 17 - Quiz

I want to draw a force with a magnitude of 300 N.
The scale must be 1 cm = 60 N
How large should the arrow (vector) be?
A
2 cm
B
5 cm
C
10 cm
D
12 cm

Slide 18 - Quiz

Topic 4.1: Forces
Adding up forces (resultant force)

Two forces in the same direction are added up

Two forces in opposite direction are subtracted from eachother

If forces are equal and in opposite direction, there is no motion!

Slide 19 - Slide

What is the resultant force?
A
140 N to the left
B
140 N to the right
C
60 N to the left
D
60 N to the right

Slide 20 - Quiz

What is the resultant force?
A
225 N to the left
B
225 N to the right
C
25 N to the left
D
25 N to the right

Slide 21 - Quiz

Topic 4.1: Forces
Adding up forces that are not in one line

Head-tail method

begin to end = resultant force

Slide 22 - Slide

Forces can't be seen.
What effects of a force can be seen?
A
changes in shape
B
changes in temperature
C
changes is color
D
changes in density

Slide 23 - Quiz

A person on earth has a mass of 80 kg. What is the gravitational force?
Only give your answer and unit

Slide 24 - Open question

Topic 4.1 : Forces
Learning goals:
  • I can explain what a force is and can identify different types of
    forces.
  • I can calculate the gravitational force acting on an object.
  • I can draw arrows on a force diagram,
                 with the correct point of
    application, magnitude and direction. 
  • I can calculate the resultant force of forces going
                 in the same
    direction or opposite directions of each other. 
  • VWO ONLY - I can calculate the resultant force

Slide 25 - Slide