# Structures and Forces

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Structures and Forces

## 1. the weight being carried or affecting an object

### 1.1. center of gravity

1.1.1. the point of an object where the weight is most concentrated in.

1.1.1.1. For example in this picture the rocks are very stable because it has a low center of gravity.

1.1.1.2. This birds center of gravity is at the beak so people can place their fingers and it will balance it.

1.2.1. the gravity affecting on a structure or object.

1.2.1.1. For example when an apple falls it drops to the ground, do to gravity the apple is being attracted to the center of the earth.

1.2.1.2. An example is when a building is falling gravity is acting on the structure making the building fall down

1.3.1. the force affecting an object or structure like wind.

1.3.1.1. For example during fall the trees lose their leaves and the wind which is a dynamic load helps the leaves fall.

1.3.1.2. For example during the winter it will snow and high winds will hit the snowflakes causing them to blow anywhere.

1.4.1.1. A person's weight is dead load because it is the weight of the structure

1.5.1. live load is a object that is being carried by another object like a bag.

1.5.1.1. A person on a boat is a live load because the boat is the dead load, all the things on the boat are live load as well.

1.5.1.2. When you pick up someone that person is the live load because the person carrying the other guy is the dead load.

## 2. Form

### 2.1. The way a structure looks.

2.1.1. symmetry

2.1.1.1. balanced arrangement on opposite sides of a structure

2.1.1.1.1. An example is a cube if you cut the cube in half they both are equal and congruent.

2.1.1.1.2. If you were to split this bridge in half you would see that both sides are equal and have symmetry.

2.1.2. stability

2.1.2.1. ability of a structure to maintain or resume its position.

2.1.2.1.1. An example is a house it has a wide base and a basement to keep it stabile.

2.1.2.1.2. An example is a 3D shape like a triangular based pyramid, on the bottom of the pyramid it is wide so the pyramid does not fall.

## 3. Internal Forces

### 3.1. compression

3.1.1. the action of something being compressed to change its form

3.1.1.1. When you are giving someone CPR you are compressing someones chest to try to get your victim to live.

3.1.1.2. When you hit a nail with a hammer it is compression because it is pushing the nail into the wood causing the wood's form to change.

### 3.2. shear

3.2.1. force that pushes in opposite directions

3.2.1.1. An example is one two people are fighting over a toy they tug on each end of the toy causing shear.Also in the game tug of war each side pulls from a different direction

3.2.1.2. When you stretch a rubber band you are causing shear because you pulling the rubber band on both of its ends.

### 3.3. tension

3.3.1. A force that stretches apart an object to expand it or lengthen it.

3.3.1.1. When you stretch you feel tension is your arms,legs,torso,etc.

3.3.1.2. A rubber band has tension when you stretch it out far enough. A rubber band has tension when it is pulled to the limit to support itself

### 3.4. torsion

3.4.1. a force that twists the object or structure

3.4.1.1. When you twist your hair you are making your hair feel torsion when to twist to much.

3.4.1.2. A example could be when you are playing badminton, you might will twist your body to hit the shuttlecock.

## 4. force

### 4.1. a physical action or strength or movement

4.1.1. point of application

4.1.1.1. the point in which the force is being applied.

4.1.1.1.1. A soccer ball being kicked in to a net needs a point of application to know where you will hit the ball so it will go in the net.

4.1.1.1.2. A basketball being shot into a hoop is point of application because the point the force is being applied is the bottom of the ball.

4.1.2. plane of application

4.1.2.1. the level/angle where you put force on an object

4.1.2.1.1. When you use a wrecking ball to knock down and destroy building you would put in consideration of the angle you will hit the object and that is plane of application

4.1.2.1.2. When you are cutting down trees with an axe you use different types of angles because the bigger the angle is the stronger the hit and faster the hit will be this is plane of application

4.1.3. gravity

4.1.3.1. The force that attracts things to the center of the earth.

4.1.3.1.1. A person is an example of gravity because the person is being pulled down by gravity making It so that don't float into the space.

4.1.3.1.2. When you throw a ball gravity is acting on the ball making it drop to the floor.

### 4.2. Magnitude

4.2.1. Magnitude is the strength put in to the object.

4.2.1.1. For example when you put things in a wagon you are putting strength on to the wagon

4.2.1.2. When you are punching something like a punching bag you can punch it hard using your strenght

## 5. function

### 5.1. the way a structure works or the purpose of it

5.1.1. sensor

5.1.1.1. A sensor detects a certain element like fire or smoke.

5.1.1.1.1. A button on an elevator wall is a sensor that detects what lobby or floor you want to go to.

5.1.1.1.2. On a iPhone 5s and up have a sensor on the button to detect your finger print which unlocks the phone

## 6. structures

### 6.1. the arrangement of pieces build to make one thing.

6.1.1. Combination structure

6.1.1.1. An object that is built with a mix of materials and other structures

6.1.1.1.1. A house is a combination structure because it is hollow in the inside like a shell structure, it is made up of a frame and the walls are solid and strong.

6.1.1.1.2. An airplane is a combination structure because it has the body as the solid the wings are the frame and then the middle is the shell.

6.1.2. frame structure

6.1.2.1. A structure that can break if one part is broken. A structure made up of a frame

6.1.2.1.1. A bicycle is a frame structure because if one part breaks the structure will fall apart.

6.1.2.1.2. A radio tower because if one part of the tower breaks the tower will fall or stop working.

6.1.3. shell structure

6.1.3.1. a structure that is hollow in the inside

6.1.3.1.1. A tennis ball is a shell structure because on the inside it is hollow and not solid.

6.1.3.1.2. An igloo is a shell structure because you can live in inside it and is hollow.

6.1.4. Solid structure

6.1.4.1. A structure that is solid all the way through

6.1.4.1.1. A block in minecraft is a solid structure because it is not hollow and it is all solid.

6.1.4.1.2. An ice cube is a solid structure because it is solid all the way through and it is strong.