# Equillibrium & center of mass

Equillibrium & center of mass
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Slide 1: Tekstslide
NatuurkundeMiddelbare schoolvmbo lwooLeerjaar 2,3

In deze les zitten 41 slides, met interactieve quizzen, tekstslides en 5 videos.

Lesduur is: 1 min

## Onderdelen in deze les

Equillibrium & center of mass

#### Slide 2 -Tekstslide

You know how to determine the center of mass
You can explain the difference between stability and equillibrium
You can explain what to do to make something more stable

0

Equillibrium

#### Slide 9 -Video

How is this possible?

#### Slide 10 -Tekstslide

How is this possible?

Can you try to explain the bird balancing on your finger?

#### Slide 11 -Open vraag

How is this possible?

#### Slide 12 -Tekstslide

How is this possible?

Can you try to explain why this construction
does not fall to the ground?

#### Slide 13 -Open vraag

Center of mass
Every object has a center of mass.

If the point of application of a force originates in the center of mass of an object, the object will follow a linear acceleration without an angular acceleration.

#### Slide 15 -Tekstslide

Stability
An object could be in a state of equillibrium even if it is unstable.

A state of equillibrium is reached when all forces and moments equal each other out.

If an object is stable or unstable depends on how easy it is for the center of mass to get outside of the support area.

The higer the center of mass is situated and the smaller the support area, the more unstable an object will be.

#### Slide 16 -Tekstslide

Drag to the corresponding red box
MOST STABLE
in between
LEAST STABLE
A
B
C

#### Slide 17 -Sleepvraag

Drag to the corresponding red box
EQUILLIBRIUM
NO EQUILLIBRIUM
A
B
C

#### Slide 21 -Tekstslide

So tell me

What do you need for a stable equillibrium?

#### Slide 22 -Open vraag

Equillibrium 1
When all forces equal each other out.
The resultant force (also called netforce) = 0 N

The object will be in rest.

It either wil not move, or only move with a constant speed.
It wil not start to change its speed, direction or shape

#### Slide 23 -Tekstslide

Equillibrium 2

In both situations there is an equillibrium.

As you can see all forces equal each other out,
since both boys have the same mass and are
sitting at the same distance from the middle.

#### Slide 24 -Tekstslide

Equillibrium 3
There are situations possible in which there  is no
equillibrium even though all forces equal each other out.

To have an equilibrium, not only all forces need to cancel
each other out, the rotational effects need to cancel
each other out as well.

Equillibrium
Only when:

all forces canceleach oher out:
the resultant force =  0 N

And

all moments (the clockwise and anti clockwise rotational effect)
cancel each other out. The resultant moment = 0 Nm

#### Slide 25 -Tekstslide

Equillibrium

1. Resultant force is zero
2. Resultant moment is zero
keep in mind
that:
stability is not the same as equillibrium
1. Low center of mass
2. Large support area
3. Large mass
Stability

#### Slide 30 -Tekstslide

Which object is more stable?
A
A
B
B

#### Slide 31 -Quizvraag

Three cans of coke.
The first is full.
The second has been emptied halfway.
The third is totally empty.
Which can is the most stable?

#### Slide 32 -Open vraag

Challenge: Can you balance a can of coke on its side.

Make a photo if you succeeded.

#### Slide 33 -Open vraag

An object tumbled over

Can you mention some causes?

#### Slide 34 -Open vraag

Using that what you have just learned, can you explain why the Fosbury Flop makes you jump higher than before?

#### Slide 38 -Tekstslide

Make chapter 4 paragraph 1 question 18 till 22

During last lessonUp: (Drawing) Forces
we already discussed most of paragraph 2, so next time go back to the first lessonup (Forces) and work on questions 23 till 36 + 39 and 40.