FORCE

When the teacher says “Hay”, students must answer “hello”, after it was noticed.

Explain the definition of force

why do we have to learn Force?

Newton’s Laws

Identify the kinds of force Draw and measure forceCalculate force resultantFrictional forceWeight

the definition of force

But really, your style was

like a professional

Ah..tidak

juga, biasa

saja kok

playing swing

playing swing Ilustration

swing can moves because there is a pull oar push.

push or pull

playing tug of war

pull

Playing tug of war illustration

Occurred Attraction between two opposing

groups

Playing football

Playing football Illustration

push occurs on the ball, so the ball moves in the direction of

the kick or push

push

Force is push or pull that can cause something moves or on

the contrary causes the moving thing to be a rest,

THE KINDS OF FORCE

As an illustration to understand and explore the kinds of force. Let us see an example of the events that happen around us

falls from heights

falls from heights

there is a force pulled it down? Why do people fall towards the bottom?

Non contact forces is a force that isn’t directly in contact with an object.

Non Contact Force

Pushing a cart

why cart can run?

Contact forces is a force that is directly in contact with an object. There are two kinds of forces work, they are frictional force and normal force.

Contact Force

Contact forces is a force that is directly in contact with an object. There are two kinds of forces work, they are frictional force and normal force.

Non contact forces is a force that isn’t directly in contact with an object.

Force based on properties

Which include a contact force?

Which include a non contact force?

Force based on its causethe

following

explanation

Muscular Force

Muscular force is a force that

comes from muscular

power

Muscular force

Spring Force

Spring force is a force that

comes from a spring, because

the spring is pulled or pushed

Spring force

Frictional force

Magnet force is a

force produced

by magnet

Magnet force

NCF

frictional force which is parallel

to the contacting

plane.

Frictional force

Electric force is a

force produced

by electrical charges

Electric force

NCF

Gravitational force is

the attractional

force caused by the earth.

gravitational force

NCF

Machine force is a force that

comes from machine.

Machine force

What can be

produced by force?

Demonstrasi toy wax, a table, marble

From the demonstration, force can produce changes1.A still object

becomes a moving object

2.A moving object becomes a still

object3.Change the shape and size of an object

4.Change the moving direction of an

object

Force can be measure using a spring balance or dynamometer.

The unit of force in the International System (SI) is the Newton.another unit of force is the dyne.

How can we measure force?

How to draw force?

Force is a quantity

which has a magnitude

and direction . So, in

physics is consid

ered a

vector quantity

. And

graphically

represented as an

arrow, called a vector

diagram.

How to draw the sum of forces?

How to draw the difference of

forces?

FORCE RESULTANTTwo force acting an object can be replaced by one force. The equivalent force is called the resultant force an is represented by R.

How can forces be in equilibrium?

1.The resultant of force is aligned and unidirectional

2. The resultant of force is aligned but in the opposite unidirectional

example

Ferdi push a table with a 300 N force to the right, while Abi push the same table with a 200 N force to the left.

The resultant of the two forces and its

direction is

What is FRICTIONAL

FORCE?

Friction is one example of a contact force since it produced by direct between two surfaces.

The direction of friction is the opposite of the tendency of moving direction of an object.

Magnitude and properties of friction force

1. The rougher the surface, greater the friction. On the other hand, the smoother the surface, the smaller the friction.

2. Direction frictional force always opposite with force

Application frictional force in

daily life

1. Disadvantage friction between a car

and the air slow down the moving speed

2. Advantage We walk on the ground

WEIGHT AND MASS

The difference between weight and

massMass Weight

Not depending gravitational acceleration

Depending gravitational acceleration

Always remain Different

Main quantity Derivative quantity

scalar quantity Vector quantity

the measuring instrument balance

The measuring instrument spring balance (dynamometer)

The unit is kg The unit is N

The relationship between mass and

weight

W = m g

example

The mass of an object with 19.6

N weight and with 9.8 N/kg gravitational

acceleration is ………

QUIZ 1

An object weighed in a location with 30 N/kg gravity. The weighing result is 15 N.

what is the mass of that object?

The mass of an object located on earth is 120 kg. if

the earth’s gravitational acceleration is 9.8 N/kg and

the moon’s gravitational acceleration is 1/6 of the earth’s. what is weight of

the same object on the moon?

QUIZ 2