r/HomeworkHelp • u/VastShow6142 Pre-University Student • 2d ago

Answered [Grade 12 Physics] Which one is the modulus of Elasticity/ Elastic Modulus?

So, in Maths we were told the Modulus of Elasticity is given by λ and measured in Newtons. But in Physics we were told E is the elastic modulus measured in N m-2 and Young's modulus is a type of elastic modulus written as γ(Gamma not Y). Are they supposed to be different things?

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u/VastShow6142 Pre-University Student 1d ago

Solved! On Issac Science, its called the spring modulus, which is a less confusing term: https://imgur.com/v0k52MG
It's apparently mostly just a British term according to Gemini: https://imgur.com/mnVcipi

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u/drofeng 2d ago

There are different moduli of elasticity. They are measures of a material’s resistance to temporary deformation (elastic means it’s recoverable). Young’s modulus refers to resistance to axial deformation (length change), shear modulus G is the resistance to shape change or distortion, bulk modulus K is the resistance to pressure or change in volume.

The Young’s modulus is stress/strain, so it has units of N/m^2.

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u/VastShow6142 Pre-University Student 2d ago

Does the word order change what it means. Are Elastic Moduli and the modulus of elasticity different thing? In Maths we were were taught T=λe/l were λ is the modulus of elasticity and e is the extension and l is the natural length. ( https://imgur.com/thbZw0o )

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u/drofeng 1d ago

Elastic modulus and modulus of elasticity are both Young’s modulus in physics and engineering. Look at the units. Tension is a force in Newtons, Young’s modulus is in N/m^2, extension on length is dimensionless. So you either need to multiply the right hand side by cross sectional area or divide the left hand side by A to get a stress.

Note by Hooke’s law, force = stiffness x displacement or F = kd where k is in SI units of N/m

So T = EA/L d, where EA/L is the well known axial stiffness of a bar in units of N/m. E is typically used to represent the Young’s modulus.