Agricultural/Bioengineering Strength of Materials 2

Question 1

A steel grain bin support column has a cross-sectional area of 0.005 m² and carries an axial compressive load of 50 kN. What is the compressive stress?

Accepted Answer

10 MPa

Answer

5 MPa

Answer

25 MPa

Answer

50 MPa

Question 2

Which of the following materials has the highest modulus of elasticity (stiffness) and is commonly used in agricultural machinery frames?

Accepted Answer

Structural steel

Answer

Polyethylene

Answer

Aluminum alloy

Answer

Douglas fir timber

Question 3

A wooden irrigation flume beam spans 4 m and carries a uniformly distributed load. If the maximum bending moment is 8 kN·m and the section modulus is 0.002 m³, what is the bending stress?

Accepted Answer

4 MPa

Answer

1 MPa

Answer

16 MPa

Answer

4000 MPa

Question 4

In a thin-walled cylindrical silo storing grain, which stress is approximately twice the longitudinal (axial) stress when internal pressure acts?

Accepted Answer

Hoop (circumferential) stress

Answer

Shear stress

Answer

Bearing stress

Answer

Torsional stress

Question 5

A tractor drawbar pin experiences a shear force of 20 kN across two shear planes (double shear). If the pin diameter is 20 mm, what is the average shear stress?

Accepted Answer

15.9 MPa

Answer

31.8 MPa

Answer

63.7 MPa

Answer

127.3 MPa

Question 6

What does the 'neutral axis' of a beam cross-section represent during bending?

Accepted Answer

The axis where bending stress is zero

Answer

The axis of maximum shear stress

Answer

The axis of maximum deflection

Answer

The centroid of the load distribution

Question 7

A cast iron pump housing in an irrigation system is subjected to a tensile stress of 80 MPa. If the ultimate tensile strength of the cast iron is 200 MPa, what is the factor of safety?

Accepted Answer

2.5

Answer

0.4

Answer

1.25

Answer

16,000