Question

A 10cm cube of basalt is compressed 1mm in the vertical direction by a large compression machine. The Elastic Modulus of Basalt is 80000MPa. How much stress in MPa does the machine apply over the cube's upper surface?

A) 800
B) 0.4
C) 80
D) 80000

Answer 1

Using the formula for stress and given the Elastic Modulus of Basalt, we calculate the stress applied to the basalt cube as 800 MPa. Hence, the correct answer is A) 800 MPa.

Step-by-step explanation:

To calculate the stress applied by the compression machine on the 10cm cube of basalt, we first need to understand that stress (σ) is defined as the force (F) applied per unit area (A). Mathematically, σ = F / A. The elastic modulus (E) of a material relates the stress to the strain (ε) in the material through the equation E = σ / ε, where strain is the relative deformation of the material, ε = ΔL / L, with ΔL being the change in length and L the original length.

For this question, we have:

• Elastic Modulus of Basalt, E = 80000 MPa
• Original length, L = 10 cm
• Change in length, ΔL = 1 mm = 0.1 cm

First, we need to calculate the strain:

ε = ΔL / L = 0.1 cm / 10 cm = 0.01

Now, we calculate the stress using the elastic modulus:

σ = E × ε = 80000 MPa × 0.01 = 800 MPa

Therefore, the correct answer is A) 800 MPa, which is the amount of stress the machine applies over the cube's upper surface.