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Nepal Engineering Council Registration Exam Strength of Materials: practice questions

Nepal Engineering Council Registration Exam — Agricultural Engineering · Nepal · Nepal Engineering Council

Original practice questions written to the published syllabus · not past papers
10worked here, free
19written to this exam in this subject
12syllabus units

About Nepal Engineering Council Registration Exam

Nepal Engineering Council Registration Exam — Agricultural Engineering is a licensing and registration exam run by Nepal Engineering Council, for candidates in Nepal.

Official site: nec.gov.np.

We have not been able to confirm these details against the exam body's own specification, so fees, dates and pass marks are left out on purpose. Check the current format, eligibility, fees and dates on the official site.

Strength of Materials in Nepal Engineering Council Registration Exam

How members carry load: stress, strain, bending, torsion, deflection and buckling, used in machine and structure design.

Our 19 Nepal Engineering Council Registration Exam questions in this subject: 11 easy, 7 medium, 1 hard, across 12 units.

10 practice questions, worked

Choose an answer, then open the working. Each explanation says why the right answer is right and why the others are not.

These 10 were written to Nepal Engineering Council Registration Exam and are not shown on any other exam's page.

Question 1 · hard

A 100 m long steel cable hangs freely down a deep bore well, carrying only its own weight. With density 7850 kg/m³ and E = 200 GPa, its elongation under self-weight is closest to:

  1. 3.85 mm
  2. 1.93 mm
  3. 0.193 mm
  4. 19.3 mm
Answer and working

B. 1.93 mm

Self-weight elongation δ = ρgL²/(2E) = 7850 × 9.81 × 100²/(2 × 200 × 10⁹) = 1.925e-03 m = 1.93 mm. Forgetting the ½ (treating the whole weight as an end load) gives 3.85 mm. 0.193 mm and 19.3 mm are decimal slips.

Question 2 · easy

The number of independent elastic constants needed to describe a homogeneous, isotropic, linear-elastic material is:

  1. Three
  2. Two
  3. Four
  4. Twenty-one
Answer and working

B. Two

Of E, G, K and ν only two are independent; the others follow from E = 2G(1 + ν) = 3K(1 − 2ν). Twenty-one is the count for a fully anisotropic material.

Question 3 · medium

A steel bolt passes through a brass tube and the nut is snug with no initial stress. The assembly is then heated uniformly. Brass has the larger coefficient of expansion. After heating:

  1. The brass tube is in compression and the steel bolt in tension
  2. The steel bolt is in compression and the brass tube in tension
  3. Both parts are in compression because both are being heated
  4. Neither part is stressed because they are free to expand together
Answer and working

A. The brass tube is in compression and the steel bolt in tension

Brass wants to grow more than steel; the steel holds it back, putting brass in compression, and the brass stretches the steel, putting it in tension. The forces are equal and opposite because there is no external load.

Question 4 · easy

For a simply supported beam carrying a uniformly distributed load over its whole span, the shear force and bending moment diagrams are respectively:

  1. A parabola and a cubic curve
  2. A sloping straight line and a parabola
  3. A horizontal line and a sloping straight line
  4. A sloping straight line and a straight triangle
Answer and working

B. A sloping straight line and a parabola

dV/dx = −w (constant), so V is linear; dM/dx = V (linear), so M is a second-degree curve, a parabola. A parabola and cubic go with a uniformly varying load; a constant V and linear M go with point loads only.

Question 5 · easy

A clockwise concentrated couple applied at a point on a simply supported beam causes, at that point:

  1. A sudden jump in the bending moment diagram only
  2. A sudden jump in the shear force diagram only
  3. Sudden jumps in both the shear force and moment diagrams
  4. A kink in the moment diagram with no jump in either
Answer and working

A. A sudden jump in the bending moment diagram only

A pure couple adds no transverse force, so V is unchanged across it, but M jumps by the value of the couple. A point load causes a jump in V and a kink in M.

Question 6 · easy

In a steel I-section beam of a farm building, most of the vertical shear force is carried by the:

  1. Web
  2. Top flange
  3. Bottom flange
  4. Flange-to-web fillet welds only
Answer and working

A. Web

Shear stress τ = VAȳ/(Ib) is small in the wide flanges and large in the narrow web, which carries most of the shear force; the flanges carry most of the bending moment.

Question 7 · medium

A 50 mm × 100 mm timber joist is used on edge (100 mm vertical) instead of flat. Its bending strength (section modulus) is increased by a factor of:

  1. 4
  2. 2
  3. 8
  4. 1
Answer and working

B. 2

Z = bd²/6: on edge 50 × 100²/6 = 83,333 mm³; flat 100 × 50²/6 = 41,667 mm³; ratio 2 (= d/b). The stiffness (I) ratio would be 4. 4 is the stiffness (I) ratio, 8 is (d/b)³, and 1 assumes strength depends only on area, which is unchanged.

Question 8 · easy

Two shafts of different diameters are joined end to end (in series) and transmit a torque. Which statement is correct?

  1. Both twist through the same angle and the torques add to the applied torque
  2. Both carry the same torque and the total twist is the sum of their twists
  3. The torque divides between them in proportion to their polar moments
  4. The smaller shaft carries less torque because it is less stiff in twist
Answer and working

B. Both carry the same torque and the total twist is the sum of their twists

In series the same torque passes through each shaft, and the angles of twist add. Equal twist with torques adding is the parallel (compound) case.

Question 9 · easy

According to the first moment-area theorem, the change in slope between two points on the elastic curve equals the:

  1. First moment of the M/EI diagram about one of the points
  2. Area of the shear force diagram between the two points
  3. Area of the M/EI diagram between the two points
  4. Difference of the bending moments at the two points
Answer and working

C. Area of the M/EI diagram between the two points

First theorem: Δθ = ∫M/(EI)dx, the area under M/EI. The second theorem uses the first moment of that area to give the tangential deviation. The SFD area gives the change in bending moment.

Question 10 · medium

An element is in a state of pure shear τ. The principal stresses and the orientation of the principal planes are:

  1. +τ and zero, on planes at 45° to the shear planes
  2. +2τ and −2τ, on planes at 90° to the shear planes
  3. +τ and −τ, on planes at 45° to the shear planes
  4. +τ and −τ, on the same planes as the shear stress
Answer and working

C. +τ and −τ, on planes at 45° to the shear planes

Mohr's circle for pure shear is centred at the origin with radius τ, so σ₁ = +τ and σ₂ = −τ at 45° to the shear planes (90° on the circle). This is why brittle materials twisted to failure break on a 45° helix.

A study plan for Strength of Materials in Nepal Engineering Council Registration Exam

This plan follows where our questions actually fall, so the time goes where the marks are likely to be. It is our reading of the syllabus, not the exam body's weighting.

  1. First, the heavy units (47% of the 19 questions): Bending and shear stresses in beams (3, 16%); Combined stresses and Mohr's circle (2, 11%); Shear force and bending moment diagrams (2, 11%); Stress, strain and Hooke's law (2, 11%).

    Read the manual chapters for these first and do every worked question you can find on them.

  2. Then the middle band: Theories of failure (2, 11%); Thermal stresses (2, 11%); Columns: Euler and Rankine formulas (1, 5%); Deflection of beams (1, 5%).

    Aim for one sitting per unit, then mixed questions across them.

  3. Then the lighter units: Elastic constants and their relations (1, 5%); Strain energy (1, 5%); Thin cylinders and spheres (1, 5%); Torsion of circular shafts (1, 5%).

    Learn the definitions, classifications and standard numbers; these units are more often recalled than worked.

  4. Leave time for the hard ones: Stress, strain and Hooke's law (1 hard of 2).

    Come back to these after a first pass, untimed, and read every explanation, including for the options you rejected.

  5. Bank the easy marks: Shear force and bending moment diagrams (2 easy of 2); Theories of failure (2 easy of 2).

    Do these early in revision so they are fast on the day.

  6. Finish timed. Sit the subject as a timed set without notes, mark it, and send each wrong answer back to its unit above.

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