# Structures and Forces

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Structures and Forces 저자:

## 1. Describing forces

### 1.1. Point of Application

1.1.1. Is a specific location where force is being used on. The side,middle,front,back or underneath.

1.1.1.1. Ex. I'm trying to hit the middle of the dart board

1.1.1.2. Ex. I'm trying to throw a basketball into the middle of the net

1.1.1.3. Ex. I'm trying to aim for the bulls eye(middle) for archery

### 1.2. Magnitude

1.2.1. Is the speed of the force being applied on a structure, object or human. Fast, medium, slow.

1.2.1.1. Ex. "Hey look at that guy! The magnitude of his soccer ball kick is so fast!"

1.2.1.2. Ex. She slowly walk, and someone says " the magnitude of her leg are slow"

### 1.3. Plane of Application

1.3.1. The face where the force is being used on, the angle 90 degrees 45 or 180 degrees.

1.3.1.1. Ex. When you are pushing the face of a cupboard, 90 degrees

1.3.1.2. Ex. Pushing a person forward or away from you, 90 degrees

1.3.1.3. Ex . When someone is pushing or pulling the door open or close, 90 degrees

### 1.4. Direction

1.4.1. Is wether the force being applied is a push or pull. Sraight or curve.

1.4.1.1. Ex. When you do a soccer kick it is a push and a curve kick, straight

1.4.1.2. Ex. When you walk the wind pushes your hair forward when it blows, straight

1.4.1.3. Ex. When you push your bed

## 2. Types of Structures

### 2.1. Solid structures

2.1.1. A structure which is most likely to be solid inside and out, but sometimes it can be hollow.

2.1.1.1. Ex. Egyptian pyramids

2.1.1.2. Ex. Mountains

2.1.1.3. Ex. Walls

### 2.2. Shell Structures

2.2.1. A shell structure is a structure that has room inside of it and is hollow. They can be used to hold things.

2.2.1.1. Ex. Tennis racks

2.2.1.2. Ex. Igloo

2.2.1.3. Ex. Egg shells

### 2.3. Frame Structures

2.3.1. A frame structure is a structure that are attached to each other to make a structure.

2.3.1.1. Ex. Spider web

2.3.1.2. Ex. Skeleton

2.3.1.3. Ex. Bridges

### 2.4. Combination Structures

2.4.1. A combination structure is a structure where all types of structures are used to form a strong building.

2.4.1.1. Ex. Car

2.4.1.2. Ex. A mall

2.4.1.3. Ex. A house

3.1.1. The movement during the structures actions.

3.1.1.1. Ex. When wind blows a boats sail

3.1.1.2. Ex. The wind blowing away a hat on a person's head

3.1.1.3. Ex. The water blowing the water affecting the surfer that is surfing

3.2.1. The object or living thing that gets supported by the dead load.

3.2.1.1. Ex. The human sitting on a chair

3.2.1.2. Ex. The person sleeping in a bed

3.2.1.3. Ex. The person driving/ inside a car

3.3.1. The object or living thing that is supporting the live load.

3.3.1.1. Ex. The car when person is driving in.

3.3.1.2. Ex. The bed when someone is sleeping in.

3.3.1.3. Ex. The chair that the human is sitting on

3.4.1. The structure's results when gravity is applied on the structure. It is a not moving load.

3.4.1.1. Ex. A school

3.4.1.2. Ex. A wall

3.4.1.3. Ex. Roof of a house

## 4. Types of Forces

### 4.1. Internal Forces

4.1.1. Torsion

4.1.1.1. Is an internal force which includes the act of twisting on a structure

4.1.1.1.1. Ex. When you open a door, you turn/twist the door nob, this is also torsion.

4.1.1.1.2. Ex. When you unlock something using a key, you must turn/twist the key in order to unlock what you need to , this is torsion.

4.1.1.1.3. Ex. When you want to get the water out of your towel you twist the water out, this is torsion

4.1.2. Tension

4.1.2.1. Is the point in a strcture,object human or animal that balances eveyrthing there is where the force of gravity acts

4.1.2.1.1. Ex. when you hurt a muscle you always stretch it out, this is tension.

4.1.2.1.2. Ex. Stretching a rubber band apart from each other

4.1.2.1.3. Ex. In synchronized skating both ends of the line have to stretch out to create tension so the line is straight.

4.1.3. Compression

4.1.3.1. Is an internal force in which includes The act of squishing on a structure

4.1.3.1.1. Ex. When you write on a paper using a pencil the lead on the pencil squishes against the paper, this is compression.

4.1.3.1.2. Ex. When you shape clay , you squish it together, this is compression.

4.1.3.1.3. Ex. When you go for a walk or a jog, your foot squishes against your shoe and your shoe compresses against the ground.

4.1.4. Shear

4.1.4.1. Is an internal force in which may include the act of bending on a structure and force in opposite directions, which may result in snapping the structure or object

4.1.4.1.1. Ex. When you open up chopsticks that are stuck together . that is shear.

4.1.4.1.2. Ex. When you want to cut paper the blades of the scissors rub against each other in opposite directions, this is shear force

4.1.4.1.3. Ex. When you bend clay to form it into different shapes it is shear.

### 4.2. External Forces

4.2.1. Friction

4.2.1.1. The action of two sides rubbing against each together

4.2.1.1.2. Ex. When you rub a balloon against you head it causes friction, that is why it can stay on the wall.

4.2.1.1.3. Ex. When you are cold you rub your hands against each other to keep thou warm, this is friction.

4.2.2. Gravity

4.2.2.1. The action among two items, which is natural

4.2.2.1.1. Ex. An object falling down like a apple falling from a tree

4.2.2.1.2. Ex. When you slide down a slide.

4.2.2.1.3. Ex. When you fall down after you jump up.

4.2.3. Push

4.2.3.1. The action of shoving something forwards by exerting force.

4.2.3.1.1. Ex. When you have a friend on the swing, you move them forward to move them. You PUSH them.

4.2.3.1.2. Ex. When you close a cabinet you had opened before you are PUSHING it closed.

4.2.3.1.3. Ex. When you are in a crowd of people you have to shove your way through, you have to push your own path in order to move.

4.2.4. Pull

4.2.4.1. The action of moving something or someone closer to you or someone else

4.2.4.1.1. Ex. When you open a cabinet you PULL the cabinet open.

4.2.4.1.2. Ex.. When you push yourself on a swing you must move yourself backwards, PULL yourself back before pushing yourself forward to create speed.

4.2.4.1.3. Ex. When you move a sleigh up a hill its easiest to PULL it.

## 6. Center Of Gravity (C.O.G)

### 6.1. C.O.G is the point in something that balances. The balancing point of a structure. That is also where force of gravity acts,

6.1.1. Ex. The centre of gravity of a human is generally near the stomach but depending on your physical appearance the C.O.G may vary.

6.1.2. Ex. The center of gravity of a pyramid is the base because most of the pyramids weight is concentrated there.

6.1.3. Ex. The center of gravity of a chair is the middle of the bottom of the chair because that is where most the weight is being concentrated on,