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Exercise 18 pag 85

We think that cast iron is tougher

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Exercise 1 page 77
ANIMAL: wool,silk.

MINERAL:marble,clay,sand.
PLANT:linen,cork.

Exercise 2 page 77

1.rock-glass-window

2.sheep-wool-scarf
3.crude oil-plastic-plastic water
4.plant-cotton-shirt
5.mineral-marble-countertop

Exercise 3 page 77

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Exercise 5 page 78

Shoe: Plastic,ledder

Partition wall: brick

Streetlight: glass,light bulb

Stay cables:plug,cables.

Exercise 6 page 78

An umbrella:Plastic :It covered its superior part to covered you from water. Fabric:It covered the internal part of the umbrella to not  break it.

A chair:Wood:It permit to you to sit down. Metal:it hold the chair up.

A frying pan:Metal:Is the place were the food fryes out. Plastic: Is were you hold the frying pan.

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Exercise 22 page 87

It will be aluminium, its the most usual metal used for cans.

Exercise 23 page 87
STATUE: We will use steel.
SARDINE TIN: We will use tin
WIRES FOR AN ELECTRICAL CIRCUIT: We will use copper.

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Exercise 9 page 79
CHAIR:

Advantages: you don´t pollute the envioroment

Disadvantages: it´s not that hard

EARRINGS

Advantages: it´s cheaper

Disadvantages: it will last more

Exercise 10 page 79

1. A car headlight: Sensory properties(Transparent),Electrical conductivity,thermal conductivity,sound conductivity,enviromental properties.

2. A mattress: Sensory properties(Opaque), Malleability,Chemical properties.

3. A golf club:chemical properties,opaque.

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Mentals that contain mainly iron are called ferrous metals. Metals that not contain iron in their composition are called non ferrous metals.

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Propierties of wood:

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Exercise 12 page 81

Natural woods:pine,ebony,beech

Man-made woods: plywood,ash,fir,chipboard,lime

Wood derivates: cork

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Mechanical properties: hard,malleable,ductile,tough

Thermal properties:good conductors, expand and contract,soldered

Electrical and magnetic properties:goood conductors,magneatic behaviour

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In this article we will learn about the various mechanical properties of materials. Knowing about them is very important
to identify any material. It is the mechanical properties which provide
the correct information about where the materials can be used. They are the
measure of strength and how long the material can exist in its service. They
play a key role in design of tools, machines and structures.

Mechanical Properties of Materials

The important mechanical properties of materials are

The stronger the material the greater the load it can
handle. Therefore it determines the ability of a material to withstand stress
without failure.

The strength of materials varies according to the types of
load.

The maximum stress that a material can withstand before
destruction is called the ultimate strength.

The tenacity of a material is the value of its ultimate
strength in tension.

Elasticity is the tensile property of the material.

3. Stiffness: The resistance of a material to elastic deformation
or deflection is called stiffness or rigidity.

A material that suffers less
deformation under the action of load possess high degree of stiffness or
rigidity.

For example a steel and aluminium beam is suspended. Both
are enough strong to carry the required load but there is a greater deflection
in the aluminium beam. This indicates that the steel beam has greater stiffness
than aluminium beam.

If the material is following Hooke's law, in that case the
stiffness of material is measured by young's modulus E. The higher the value of
the young's modulus the more will be the stiffness.

In tensile and compressive stress, it is called as modulus
of stiffness or modulus of elasticity; In shear, modulus
of rigidity; in volumetric distortion, the bulk modulus.

4. Flexibility: It is defined as the ability of the material to
bend easily. This mechanical properties of materials allows it to form in any shape.

The plastic deformation appears when the material is
stressed beyond the elastic range.

Plasticity is important in shaping, forming, extruding and
many other hot or cold working process.

Generally plasticity increases with the increase in
temperature.

6. Ductility: It is the property of a material by which it can
be drawn into thin wires. The materials that possess this property are used in
wire industries for manufacturing of wires. For example: gold, copper, iron,
mild steel etc.

8. Toughness: Toughness is defined as the ability of a material
to withstand both the plastic and elastic deformation. In other word it is the
measure of the amount of energy a material can absorb before actual fracture or
failure takes place.

The materials that possess this property are used in the
manufacturing of structural and machine parts which have to withstand shock and
vibration.

The maximum energy that can be stored in a body upto elastic
limit is called the proof resilience. And the proof resilience per unit volume
is called as modulus of resilience.

The materials having this property are used to manufacture springs.
This property gives capacity to a material to bear shocks and vibration.

11. Brittleness: It is defined as the property of breaking of materials
without much permanent distortion.

There are so many materials which break
without showing much permanent distortion. Such materials are said to be brittle
such as glass and cast iron.

Brittleness is the opposite of ductility.

12. Machinability: It is the ability of the material to be cut
easily.

The machinability of a metal in indicated by percentages which
is called machinability index. All machinable metals are compared to a basic
standard. The standard metal used for the 100 percent machinability is free
cutting steel.

The machinability index of carbon steels generally ranged
from 40 to 60 per cent and that of cast iron from 50 to 80 percent. The metals
with higher range of machinability index can machined or cut easily.

In other words it is also defined as the time dependent
strain occurring under stress.

The creep deformation occurs in a material which is exposed for
a long time to high level of stresses that are below yield strength.

There are three stages of creep.

1. In the first stage the material elongates rapidly but at a
decreasing rate.

2. In the second stage, the rate of elongation is constant.

3. In the third stage, the rate of elongation increases rapidly
until the material fails.

14. Fatigue: The phenomena of weakening of material when it is
subjected to repeated or fluctuating stress is called fatigue.

When material is subjected to cyclic or fluctuating loading, there appears
a minute cracks and these cracks grow with time and
finally the materials gets fractured.

Mechanical Properties of Materials in Tabular Form

This is all about the mechanical properties of materials. If
you find anything missing or incorrect than don't forget to comment. If you
like this article than like us on Facebook.

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Mechanical Properties of Materials - Mechanical Booster

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In this article we will learn about the various mechanical properties of materials. Knowing about them is very important to identify any material. It is the mechanical properties which provide the correct information about where the materials can be used. They are the measure of strength and how long the material can exist in its service.

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Exercise 11 page 80
WOOD

Advantages: it´s good in the longiturinal direction

Disadvantages: poor in the tranverse direction