# 4.3 Reinforcing doors and windows

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## Reinforcing doors and windows

REINFORCING, by using concrete and lintels over doors and window openings.

Stability

Structures are stabilized to prevent them from collapsing when forces or loads are put on them. To prevent a structure from falling down or collapsing we must try to make the internal forces bigger than the external forces under all conditions. How can you prevent a chair from collapsing when you sit on it? There are rails acting as ties at the bottom holding the legs together and preventing the legs from being pushed outwards.

A flagpole doesn’t need any supports under normal conditions. When the wind blows it can be supported by using guy ropes or ties that are flexible, but stop the poles from bending too far.

Different forces can act on different parts of a structure. Forces that structures have to stand up to are:

• Compression – when we try to squash a structure ( a squashing force).
• Tension – when we try to pull a structure apart from either end (a pulling force).

• Bending – a force which is trying to bend a structure and it is in compression and tension simultaneously.
• Torsion – a turning or twisting force like when you twist the top off a bottle.
• Shear – a force created when two opposite forces try to cut a material; like when you use a pair of scissors to cut a piece of paper.

When one force is balanced by another they are said to be in EQUILIBRIUM.

When you build a structure, you do not always have to use solid material like wood or metal. Flexible material, such as wire, can be used for parts of the structure which will only be stretched or in tension. Wire can be used in tension (being stretched), but not in compression (be squashed).

Load from the top of the structure keeps the wire in tension and the structure remains rigid.

When the structure is loaded from the sides the wire is compressed (squashed) and it collapses. It is unstable.

Triangles are very useful when building structures. They can help to make a very strong and rigid structure. To make a rectangle more stable is to put in two more members from corner to corner. Four triangles are formed. This way of making structures more stable is called TRIANGULATION. It is often used when building bridges or cranes. It is not always necessary to put in two members, one would be enough. The second extra member is called the redundant member. When designing structures it is easy to use more members that are really needed. They will only add more weight to the finished structure and make it more expensive.

By making the base size of a structure heavier or wider, you can also make it more stable.

## [lo 2.1]

Choice 1:

Design and make a horizontal structure using 25 paper straws and a glue gun. Your structure must support a marble as far out from the table as possible. Your structure must not come in contact with the floor or any of the other furniture in the room. It must support the marble for at least 30 seconds.

Choice 2:

Design and make a tower using 25 paper straws and a glue gun. Your tower must support a marble for at least 30 seconds as high as possible.

It is also important to get a structure’s centre of gravity so that it is able to balance. All objects have a point where they are held in balance by the force of gravity. This balancing point is called the centre of gravity, because it is the place where the whole weight of the object seems to centre. The balancing point of a rectangular shape, such as a square or a circle, is in the centre.

How can you find the balancing point of an irregular shape?

Where do you think is the best place for the heavy cargo to be stowed on a ship?

Gravity is the pull that objects have on other objects around them. Because the Earth itself is the largest object in our world, the pull of its gravity is the strongest we can feel. Gravity keeps everything resting on the ground. An object centre of gravity is found when it just balances on the edge of a table before it falls off.

Any object will balance on a pivot when its centre of gravity is low.

How can you change an object’s centre of gravity?

## [lo 2.1]

Requirements :

• Thick white card
• a drawing pin
• a scissors
• felt tip pens
• strong glue
• wire
• 2 plasticine balls
• a heavy bottle
• a glue gun
• pliers

Method:

1. Draw the man shape onto some thick white card. Carefully cut out the shape with scissors.

1. Colour in the man to make him more human in the front and back using felt tip pens. Carefully glue a drawing pin to the bottom of the card.

1. Cut of a length of wire using pliers. Glue it into place with the glue gun.

1. Glue two plasticine balls to each end of the wire.

4. Carefully stand the balancing man on top of a bottle. He wobbles slightly, but should keep his balance.

JOINING TECHNIQUES

 Paper/card Glue, paper clips, a stapler, paper fasteners, washers, string or yarn, tape, pins Textile Textile glue glues material onto material, PVA glue glues material to paper, card or wood, string , yarn, fasteners (buttons, velcro, zips, hooks and eyes, snap-fasteners, press-studs, strings, laces, ribbon) Wood Nails, pins, screws, woodglue, joints Metal Screws, bolts and nuts, soldering, glue, rivets Plastic Screws, glue

## Assessment

 Assessment standards (ASs) We know this when the learner: structures: 2.1 demonstrates knowledge and understanding of structures. processing :2.2 demonstrates knowledge and understanding of how materials can be processed to change or improve properties (e.g. strength, fire resistance, waterproofing, taste, volume, texture).

where we get a research paper on Nano chemistry....?
nanopartical of organic/inorganic / physical chemistry , pdf / thesis / review
Ali
what are the products of Nano chemistry?
There are lots of products of nano chemistry... Like nano coatings.....carbon fiber.. And lots of others..
learn
Even nanotechnology is pretty much all about chemistry... Its the chemistry on quantum or atomic level
learn
da
no nanotechnology is also a part of physics and maths it requires angle formulas and some pressure regarding concepts
Bhagvanji
hey
Giriraj
Preparation and Applications of Nanomaterial for Drug Delivery
revolt
da
Application of nanotechnology in medicine
what is variations in raman spectra for nanomaterials
ya I also want to know the raman spectra
Bhagvanji
I only see partial conversation and what's the question here!
what about nanotechnology for water purification
please someone correct me if I'm wrong but I think one can use nanoparticles, specially silver nanoparticles for water treatment.
Damian
yes that's correct
Professor
I think
Professor
Nasa has use it in the 60's, copper as water purification in the moon travel.
Alexandre
nanocopper obvius
Alexandre
what is the stm
is there industrial application of fullrenes. What is the method to prepare fullrene on large scale.?
Rafiq
industrial application...? mmm I think on the medical side as drug carrier, but you should go deeper on your research, I may be wrong
Damian
How we are making nano material?
what is a peer
What is meant by 'nano scale'?
What is STMs full form?
LITNING
scanning tunneling microscope
Sahil
how nano science is used for hydrophobicity
Santosh
Do u think that Graphene and Fullrene fiber can be used to make Air Plane body structure the lightest and strongest. Rafiq
Rafiq
what is differents between GO and RGO?
Mahi
what is simplest way to understand the applications of nano robots used to detect the cancer affected cell of human body.? How this robot is carried to required site of body cell.? what will be the carrier material and how can be detected that correct delivery of drug is done Rafiq
Rafiq
if virus is killing to make ARTIFICIAL DNA OF GRAPHENE FOR KILLED THE VIRUS .THIS IS OUR ASSUMPTION
Anam
analytical skills graphene is prepared to kill any type viruses .
Anam
Any one who tell me about Preparation and application of Nanomaterial for drug Delivery
Hafiz
what is Nano technology ?
write examples of Nano molecule?
Bob
The nanotechnology is as new science, to scale nanometric
brayan
nanotechnology is the study, desing, synthesis, manipulation and application of materials and functional systems through control of matter at nanoscale
Damian
Is there any normative that regulates the use of silver nanoparticles?
what king of growth are you checking .?
Renato
What fields keep nano created devices from performing or assimulating ? Magnetic fields ? Are do they assimilate ?
why we need to study biomolecules, molecular biology in nanotechnology?
?
Kyle
yes I'm doing my masters in nanotechnology, we are being studying all these domains as well..
why?
what school?
Kyle
biomolecules are e building blocks of every organics and inorganic materials.
Joe
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