Solving Young's Modulus: Help Needed

In summary, the conversation is about a problem related to Young's Modulus. The person asking for help has tried to solve the problem but got the wrong answer. They are seeking clarification on where they went wrong and how to properly calculate the Young's Modulus. The problem involves a brass wire experiencing an elongation of 0.49mm under a tensile force of 1.0 kN and the calculation requires the values for stress, strain, and cross-sectional area. It is mentioned that the answer should be 1.3*10^11, while the person's calculation resulted in 1.0*10^7. It is later revealed that the cross-sectional area and length values used were incorrect, leading to a
  • #1
KaneOris
113
0
Youngs Modulus

Hey guys, i tried this problem on youngs modulas and got the wrong answer

So i was wondering if anyone could tell me where i went wrong here or tell me how to do it properly.

Problem:

A 20cm brass wire of radius 1.0mm
experiences an elongation of 0.49mm
when a tensile force of 1.0 kN is applied.
Calculate the youngs modulas of brass.

E=σ/Є
σ = F/A
Є=ΔL/L

F=1000 N
A=0.2*0.001
ΔL=4.9*10^-4
L=1.0*^-3

Є = 4.9*10^-4/1.0X10^-3
σ = 1000/0.2*0.001
E= (1000/0.2*0.001)/(4.9*10^-4/1.0X10^-3)
That came out as 1.0*10^7 for me.
The answer is apparently 1.3*10^11

Any help on this would be good.
 
Last edited:
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  • #2
The cross sectional area is wrong...

Daniel.
 
  • #3
mmm, wires, 3.142r^2...
 
  • #4
Yep,that's right.And the length L is wrong as well.

Daniel.
 
  • #5
calculation mistake rather than conceptual mistakes..
 

1. What is Young's Modulus?

Young's Modulus, also known as the modulus of elasticity, is a measure of the stiffness of a material. It is the ratio of stress to strain within the elastic limit of a material, and is typically expressed in units of pressure, such as pascals (Pa).

2. How is Young's Modulus calculated?

To calculate Young's Modulus, you need to measure the stress and strain of the material. Stress is the force applied to a material per unit area, while strain is the resulting deformation of the material. Young's Modulus is then calculated by dividing the stress by the strain.

3. What is the importance of Young's Modulus?

Young's Modulus is an important property of materials as it helps to determine their strength and stiffness. It is used in engineering and construction to ensure that materials can withstand the forces they will be subjected to, and to design structures that can support these forces.

4. What are the factors that can affect Young's Modulus?

The main factors that can affect Young's Modulus are the type of material, its composition, and its microstructure. Other factors such as temperature, pressure, and stress can also impact Young's Modulus.

5. How can Young's Modulus be measured?

Young's Modulus can be measured using various methods such as tensile testing, bending tests, or compression tests. These tests involve applying a known stress to a material and measuring the resulting strain to calculate its Young's Modulus.

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