High School

4. A rectangular bar, 75mm wide by 50mm thick, extends 2mm on a length of 1.5m under a axial force of 1MN. If the corresponding decrease in width is 0.0275mm, calculate the value of Young's modulus and Poisson's ratio. What would be the thickness under a force of 800KN? 200GPa; 0.275; 0.01467]

Answer :

The value of Young's modulus is approximately 133.33 GPa, the value of Poisson's ratio is approximately -0.01375 and the thickness under a force of 800 kN is approximately 0.800 mm.

To calculate the values of Young's modulus (E) and Poisson's ratio (ν), we can use the formulas:

E = (F * L) / (A * ΔL)

ν = -ΔW / ΔL

where:

F is the axial force (1MN = 1,000 kN = 1,000,000 N)

L is the original length (1.5m = 1,500mm)

A is the original cross-sectional area (A = width * thickness)

ΔL is the change in length (2mm)

ΔW is the change in width (0.0275mm)

Let's calculate these values:

Calculate the original cross-sectional area (A):

A = width * thickness

A = 75mm * 50mm

A = 3750 mm²

Calculate Young's modulus (E):

E = (F * L) / (A * ΔL)

E = (1,000,000 N * 1,500 mm) / (3750 mm² * 2 mm)

E = 1,000,000,000 N mm / (7,500,000 mm³)

E = 133.33 GPa

Therefore, the value of Young's modulus is approximately 133.33 GPa.

Calculate Poisson's ratio (ν):

ν = -ΔW / ΔL

ν = -0.0275 mm / 2 mm

ν = -0.01375

Therefore, the value of Poisson's ratio is approximately -0.01375.

To find the thickness under a force of 800 kN, we can use the formula:

thickness = (F * L) / (A * E)

Let's calculate the thickness:

Convert the force to Newtons:

800 kN = 800,000 N

Calculate the new thickness:

thickness = (800,000 N * 1,500 mm) / (3750 mm² * 133.33 GPa)

thickness ≈ 0.800 mm

Therefore, the thickness under a force of 800 kN is approximately 0.800 mm.

To learn more about Young's modulus visit:

brainly.com/question/13257353

#SPJ11