#### Transcript of Uses of Young's Modulus

**Uses of Young's Modulus**

What is Young's Modulus?

Stress and Strain

Who uses Young's Modulus?

Engineers

Stress is the measure of force exerted on the object over the cross-sectional area of the material.

Strain, on the other hand, is the change in the length of the material over the original length.

Both of these two measurements are vital parts of Young's Modulus.

It is used by engineers to make sure their materials can withstand a sufficient amount of force for the product they are designing.

An example of this would be tests a structural engineer would run on the materials being used to build a bridge, ehich eventually leads to a weight limit being found which is specific to that bridge.

Physicists

The equation of Young's Modulus

Physicists would also use Young's Modulus to test materials and equipment to see how strong they are before using them in high pressure experiments.

Young's Modulus is used as a way of determining the stiffness of a substance.

It is found by dividing the stress of an object by the strain.

This is only spplicable though where Hooke's law applies.

Engineering

These are a couple of examples of where Young's Modulus is used in engineering.

All of these items require very high strength and therefore the use of Young's Modulus is essential.

Application - Guns

Poisson ratio

When an object is compressed in one direction, it expands in the other

Application of the calculations

Young's Modulus and Poisson ratio are used for gun barrel steel.

(the cartridges referenced are CDA 260 cartridge - brass)

Some more examples

Concrete

Concrete will fail without any warning so if the limit is broken the whole structure collapses.

But steel has a reduction in stress so you can tell when it is about to collapse, meaning action can be taken, such as evacuating.

Diamond

Our aim:

Diamond is the stiffest material because of its full covalent bonding but the high price means its not used for engineering applications.

Explain how Young's Modulus is used in the working world of engineers and physics

Even more examples

Polymers

Polymers aren't a good choice for stiff, cheap products - but they can be reinforced by incorporating stiffeners into the design

Polyethene

Polyethene has a wide range for Young's Modulus because the 'bubble' on a Young's Modulus-time graph includes both LDPE and HDPE

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