Stress (Mechanics)

TwF Embedded in a Section

Stress is the force per unit area on or within a material that arises in response to externally applied loads.

id: 1761842051

# Task

- Common units on stress? 
- Secondary Dimensions?
- Primary Dimensions? 

# Feedback

- Units. Pa, psi, N/m^2
- Secondary Dimensions: F/A = Force/Area, Mass*Acceleration/Area
- Primary Dimensions: M/L*T^2

TwFs in Their Own Section

id: 1761842456

# Task

A 2000 pound weight hangs from a vertical 1 inch diameter steel rod. Caculate the average stress in the rod in SI units. 

# Feedback

1. stress = force/area
2. force is 2000 lbf = 8896.4 N
3. $A = \pi * D^2/4 =  0.0005067 \text{m}^2$
4. Thus, stress = 8896.4 N / 0.0005067 m^2 = 17.6 MPa

id: 1764256966

# Task 

Convert to SI: $/sigma=10$ ksi

# Feedback

- 10 ksi = 10,000 psi
- 1 psi ≈ 6894.757 Pa
- 10,000 psi × 6894.757 Pa/psi ≈ 6.8948 × 10^7 Pa
- Therefore: 10 ksi ≈ 69 MPa

id: 1764257380

# Task

Typical yield strength from mild steel in SI and US units.

# Feedback

- 250 MPa
- 36 ksi