Y2_T4_LSN4.1

• Science
• Middelbare school
• havo, vwo
• Leerjaar 2

Topic 4

MOVEMENT IN THE WORLD

GRADES:

QUIZ (2X)

TEST (4X)

§4.1 Forces

p. 154-157

ex 1-11 p 158-161

Check out plan in magister!

§4.1 - 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 of two perpendicular forces 

P.154-157

§4.1 - Keywords:

• Gravity 
• Applied force 
• Air resistance 
• Friction 
• Tension force 
• Spring force 
• Normal force
• Resultant force 
• Point of application
• Direction
• Magnitude

P.154-157

F​g​​

F​a​​

F​air​​

F​f​​

F​t​​

F​s​​

F​n​​

F​res​​

A world of Forces:

Forces are all around us

• You can’t see them
• You can only see their effect

The things forces can do:

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

P.154-157

Types of Forces:

• Gravity 
• Applied force 
• Air resistance 
• Friction 
• Tension force 
• Spring force 
• Normal force 

P.154-157

F​g​​

F​a​​

F​air​​

F​f​​

F​t​​

F​s​​

F​n​​

Magnitude of Forces:

Force is measured in Newtons

• The force needed to lift 1 kg = 9.81 N on earth
• On the moon the force needed is only 1.6 N
• The mass is the same
• Gravitational force is different

P.154-157

Calculation gravitational force:

•        = gravitational force in Newton or weight
• m = mass in kg
• 9.81 is a constant

P.154-157

F​g​​

F​g​​​​​=m⋅9.81

Example: Peter has a mass of 76 kg. What is his gravitational force, ?

F​g​​

Example: The gravitational force of my cat is 34.3N What is her mass?

F​g​​

Drawing Forces:

Forces are represented by an arrow

It has three things:

• point of application - origin of force
• direction
• magnitude (size) - the longer the arrow, the bigger the force

P.154-157

Adding & subtracting forces:

• Two forces in the same direction are added up

• Two forces in opposite direction are subtracted from each other

If forces are equal, there is no motion

P.154-157

Adding & subtracting forces:

• Resultant force is the sum of the forces
• It is written as 

Forces in the same direction = add

     

Forces in the opposite direction = subtract

          

P.154-157

F​res​​

Perpendicular forces:

• Combine the forces end to end by making a triangle

P.154-157

Forces worksheet:

• Open the worksheet on Google Classroom
• Try the questions by yourself first.
• Then try together
• Then ask for help

P.154-157

Hw for lesson 2:

• Complete the forces worksheet.
• Complete exercises 1-11 of §4.1 pages 158-161
• Read §4.2 pages 162-165
• Study the glossaries of §4.1-§4.2 on Studygo.

P.154-157