Strength of Materials – Moderate Level MCQs
MCQs 201–300 (SSC RRB #JE)
🔹 Stress, Strain & Elastic Constants
201. Stress in a bar of cross-sectional area A subjected to load P is
A) P×A
B) P/A
C) A/P
D) P²/A
Ans: B
Detail: Stress = Load / Area.
202. Strain is measured in
A) N
B) mm
C) m
D) No unit
Ans: D
Detail: Strain is dimensionless.
203. Young’s modulus represents
A) Strength
B) Stiffness
C) Toughness
D) Ductility
Ans: B
Detail: Higher E → more resistance to deformation.
204. Poisson’s ratio is negative because
A) Stress is negative
B) Lateral strain is opposite to longitudinal strain
C) Material shrinks
D) Volume decreases
Ans: B
Detail: Extension causes lateral contraction.
205. If μ = 0.5, material is
A) Perfectly elastic
B) Perfectly plastic
C) Incompressible
D) Brittle
Ans: C
Detail: No volume change.
206. Bulk modulus relates to
A) Linear strain
B) Volumetric strain
C) Shear strain
D) Bending strain
Ans: B
Detail: K = volumetric stress / volumetric strain.
207. Elastic limit is
A) Point of fracture
B) Maximum elastic stress
C) Maximum plastic stress
D) Yield stress
Ans: B
Detail: Beyond this permanent set begins.
208. Proof stress is used when
A) Yield point is distinct
B) Yield point is not distinct
C) Material is brittle
D) Material is rubber
Ans: B
Detail: Used for aluminium, brass.
209. Factor of safety is
A) Working stress / Ultimate stress
B) Ultimate stress / Working stress
C) Yield stress / Working stress
D) Proof stress / Yield stress
Ans: B
Detail: Margin of safety.
210. Working stress is always
A) Higher than ultimate stress
B) Lower than ultimate stress
C) Equal to ultimate stress
D) Zero
Ans: B
Detail: Safe design stress.
🔹 Axial Load & Thermal Stress
211. Elongation of a bar is proportional to
A) Area
B) Length
C) 1/E
D) Both B and C
Ans: D
Detail: δ = PL/AE.
212. If area is doubled, elongation becomes
A) Double
B) Half
C) Same
D) Four times
Ans: B
Detail: δ ∝ 1/A.
213. Thermal strain is given by
A) αΔT
B) ΔT/α
C) α/ΔT
D) α²ΔT
Ans: A
Detail: Basic expansion relation.
214. Thermal stress develops when
A) Bar is free to expand
B) Expansion is restrained
C) Bar is short
D) Temperature falls
Ans: B
Detail: Restraint causes stress.
215. In a fully restrained bar, thermal stress is
A) Tensile
B) Compressive
C) Shear
D) Zero
Ans: B
Detail: Expansion prevented.
216. In bars connected in series, which remains same?
A) Stress
B) Strain
C) Force
D) Area
Ans: C
Detail: Same axial force passes through all.
217. In bars connected in parallel, which remains same?
A) Stress
B) Strain
C) Force
D) Length
Ans: B
Detail: Equal deformation.
218. Composite bar problems use which condition?
A) Only equilibrium
B) Only compatibility
C) Both equilibrium & compatibility
D) Geometry only
Ans: C
Detail: Must satisfy both.
219. Thermal stress does NOT depend on
A) E
B) α
C) ΔT
D) Length
Ans: D
Detail: σ = EαΔT.
220. A bar under axial load stores energy due to
A) Weight
B) Temperature
C) Deformation
D) Density
Ans: C
Detail: Strain energy.
🔹 Torsion of Shafts
221. Torsion equation is
A) M/I = σ/y
B) T/J = τ/R = Gθ/L
C) P/A
D) E = σ/ε
Ans: B
Detail: Fundamental torsion relation.
222. Polar moment of inertia is denoted by
A) I
B) Z
C) J
D) A
Ans: C
Detail: Used in torsion.
223. Shear stress in a solid shaft varies
A) Uniformly
B) Linearly with radius
C) Parabolically
D) Randomly
Ans: B
Detail: τ ∝ r.
224. Maximum shear stress in shaft occurs at
A) Centre
B) Outer surface
C) Mid radius
D) Neutral axis
Ans: B
Detail: Maximum radius.
225. Hollow shaft is preferred because
A) Less weight
B) Higher strength-to-weight ratio
C) Cheaper
D) Less material
Ans: B
Detail: Better torque capacity.
226. Torsional rigidity is
A) GJ
B) EI
C) EA
D) EJ
Ans: A
Detail: Resistance to twist.
227. Angle of twist increases if
A) Diameter increases
B) Length increases
C) Modulus increases
D) Polar moment increases
Ans: B
Detail: θ ∝ L.
228. Power transmitted by a shaft is
A) NT
B) 2πNT/60
C) T/N
D) N/T
Ans: B
Detail: Standard power formula.
229. A shaft under pure torsion experiences
A) Only normal stress
B) Only shear stress
C) Both stresses
D) No stress
Ans: B
Detail: No normal stress.
230. For ductile shafts, failure theory used is
A) Rankine
B) Tresca
C) Coulomb
D) Mohr
Ans: B
Detail: Max shear stress theory.
🔹 Bending of Beams
231. Neutral axis passes through
A) Top fibre
B) Bottom fibre
C) Centroid
D) Shear centre
Ans: C
Detail: For homogeneous section.
232. Bending stress formula is
A) σ = M/I
B) σ = My/I
C) σ = Iy/M
D) σ = M/y
Ans: B
Detail: Flexure equation.
233. Maximum bending stress occurs at
A) Neutral axis
B) Farthest fibre
C) Centroid
D) Shear centre
Ans: B
Detail: y is maximum.
234. Section modulus is
A) I/ymax
B) I×ymax
C) A/y
D) y/I
Ans: A
Detail: Indicates bending strength.
235. Stronger beam section is one with
A) Larger area
B) Larger section modulus
C) Larger length
D) Larger mass
Ans: B
Detail: Bending strength criterion.
236. In cantilever beam, maximum BM occurs at
A) Free end
B) Fixed end
C) Mid span
D) Quarter span
Ans: B
Detail: Always at fixed end.
237. In simply supported beam with UDL, max BM at
A) Supports
B) Mid span
C) Quarter span
D) One-third span
Ans: B
Detail: At centre.
238. Shear force is maximum at
A) Mid span
B) Supports
C) Neutral axis
D) Free end
Ans: B
Detail: Reactions are max.
239. Point of contraflexure is where
A) BM = 0
B) SF = 0
C) Stress = 0
D) Deflection = 0
Ans: A
Detail: Change in curvature.
240. In pure bending, shear force is
A) Zero
B) Maximum
C) Constant
D) Negative
Ans: A
Detail: Only bending moment acts.
🔹 Shear Stress in Beams
241. Average shear stress in beam is
A) V/A
B) VQ/It
C) M/I
D) T/J
Ans: A
Detail: Simple formula.
242. Maximum shear stress in rectangular beam is
A) Equal to average
B) 1.5 × average
C) 2 × average
D) 0.5 × average
Ans: B
Detail: τmax = 1.5τavg.
243. Shear stress is zero at
A) Neutral axis
B) Top fibre
C) Bottom fibre
D) Outer surface
Ans: D
Detail: In rectangular section.
244. In I-section beam, shear stress is maximum at
A) Flange
B) Web at NA
C) Bottom fibre
D) Top fibre
Ans: B
Detail: Shear carried mainly by web.
245. Shear stress distribution in rectangular beam is
A) Linear
B) Uniform
C) Parabolic
D) Triangular
Ans: C
Detail: Maximum at NA.
🔹 Columns & Buckling
246. Column fails mainly due to
A) Torsion
B) Buckling
C) Shear
D) Bending
Ans: B
Detail: Stability failure.
247. Slenderness ratio is
A) L/A
B) L/k
C) A/L
D) I/A
Ans: B
Detail: k = radius of gyration.
248. Euler’s formula is valid for
A) Short columns
B) Intermediate columns
C) Long columns
D) All columns
Ans: C
Detail: Elastic buckling.
249. Critical load is
A) Yield load
B) Buckling load
C) Breaking load
D) Impact load
Ans: B
Detail: Instability load.
250. Column with both ends fixed has effective length
A) L
B) 2L
C) L/2
D) √2L
Ans: C
Detail: Strongest end condition.
251. Column with one end fixed and other free has effective length
A) L
B) 2L
C) L/2
D) √2L
Ans: B
Detail: Weakest end condition.
252. Buckling load is proportional to
A) L
B) L²
C) 1/L
D) 1/L²
Ans: D
Detail: Euler’s formula.
253. Rankine formula is applicable to
A) Short columns only
B) Long columns only
C) Intermediate columns only
D) All columns
Ans: D
Detail: Empirical relation.
254. A column will buckle in the plane of
A) Maximum I
B) Minimum I
C) Maximum area
D) Minimum area
Ans: B
Detail: Least stiffness.
255. Radius of gyration is
A) √(I/A)
B) I/A
C) A/I
D) √(A/I)
Ans: A
Detail: Measure of distribution of area.
🔹 Strain Energy & Impact
256. Strain energy in bar under axial load is
A) PL/AE
B) P²L/2AE
C) P²L/AE
D) PL/2AE
Ans: B
Detail: U = Pδ/2.
257. For suddenly applied load, maximum stress is
A) Same as static
B) Half of static
C) Double of static
D) Zero
Ans: C
Detail: Dynamic factor = 2.
258. Impact loading produces
A) Lower stress
B) Same stress
C) Higher stress
D) Zero stress
Ans: C
Detail: Due to kinetic energy.
259. Proof resilience is
A) Total strain energy
B) Elastic strain energy per unit volume
C) Plastic energy
D) Impact energy
Ans: B
Detail: Up to elastic limit.
260. Toughness is area under
A) Elastic portion
B) Plastic portion
C) Entire stress-strain curve
D) Yield region
Ans: C
Detail: Total energy to fracture.
🔹 Fatigue & Stress Concentration
261. Fatigue failure is due to
A) Static loading
B) Repeated loading
C) Thermal loading
D) Impact loading
Ans: B
Detail: Cyclic stresses.
262. Endurance limit is
A) Max stress
B) Safe cyclic stress
C) Yield stress
D) Ultimate stress
Ans: B
Detail: Infinite life below this.
263. Stress concentration occurs due to
A) Uniform section
B) Sudden change in section
C) Long length
D) Smooth surface
Ans: B
Detail: Causes local high stress.
264. Stress concentration factor is
A) Max stress / Nominal stress
B) Nominal / Max
C) Stress / strain
D) Load / area
Ans: A
Detail: Measures severity.
265. Fillets are provided to
A) Increase stress
B) Reduce stress concentration
C) Reduce weight
D) Increase length
Ans: B
Detail: Smooth geometry.
🔹 Combined Stress & Failure Theories
266. Principal stresses act on planes where
A) Normal stress is zero
B) Shear stress is zero
C) Bending stress is zero
D) Load is zero
Ans: B
Detail: Definition.
267. Maximum shear stress in biaxial stress is
A) (σ₁ + σ₂)/2
B) (σ₁ − σ₂)/2
C) σ₁
D) σ₂
Ans: B
Detail: From Mohr’s circle.
268. Tresca theory is also called
A) Maximum principal stress theory
B) Maximum shear stress theory
C) Maximum strain theory
D) Distortion energy theory
Ans: B
Detail: For ductile materials.
269. Von Mises theory is based on
A) Max shear stress
B) Max principal stress
C) Distortion energy
D) Total strain energy
Ans: C
Detail: Most accurate for ductile metals.
270. Rankine theory is used for
A) Ductile materials
B) Brittle materials
C) Rubber
D) Plastics
Ans: B
Detail: Max normal stress.
🔹 Deflection of Beams
271. Deflection of a beam is inversely proportional to
A) EI
B) L
C) Load
D) Area
Ans: A
Detail: Higher stiffness → less deflection.
272. Maximum deflection in simply supported beam with central load occurs at
A) Quarter span
B) Mid span
C) Support
D) One-third span
Ans: B
Detail: Symmetry.
273. Unit load method is used to find
A) Stress
B) Bending moment
C) Deflection
D) Torque
Ans: C
Detail: Based on virtual work.
274. Conjugate beam method is used for
A) BM
B) SF
C) Slope and deflection
D) Stress
Ans: C
Detail: Structural analysis tool.
275. Deflection varies with
A) L²
B) L³
C) L⁴
D) L⁵
Ans: C
Detail: Beam theory.
🔹 Miscellaneous
276. Hardness means resistance to
A) Bending
B) Scratching
C) Fatigue
D) Impact
Ans: B
Detail: Surface property.
277. Ductility is measured by
A) % elongation
B) % reduction in area
C) Both
D) None
Ans: C
Detail: Tensile test.
278. Cast iron is best in
A) Tension
B) Compression
C) Torsion
D) Bending
Ans: B
Detail: High compressive strength.
279. Steel is generally
A) Brittle
B) Ductile
C) Fragile
D) Soft
Ans: B
Detail: Large plastic deformation.
280. Proof resilience depends on
A) Yield stress
B) Ultimate stress
C) Breaking stress
D) Endurance limit
Ans: A
Detail: Ur = σy²/2E.
281. Neutral axis shifts when
A) Section is symmetrical
B) Section is unsymmetrical
C) Load is zero
D) Moment is zero
Ans: B
Detail: Unequal geometry.
282. Shear centre is point where
A) Load causes bending only
B) Load causes no twisting
C) Load causes shear only
D) Load causes torsion only
Ans: B
Detail: Important in thin sections.
283. A beam under transverse load experiences
A) Only axial stress
B) Only shear stress
C) Shear and bending stress
D) Only torsion
Ans: C
Detail: Main stresses in beams.
284. A shaft designed on strength basis may fail due to
A) Buckling
B) Fatigue
C) Corrosion
D) Temperature
Ans: B
Detail: Cyclic loading.
285. The weakest column end condition is
A) Hinged–hinged
B) Fixed–hinged
C) Fixed–fixed
D) Fixed–free
Ans: D
Detail: Effective length = 2L.
286. A beam with constant bending stress is called
A) Uniform beam
B) Beam of uniform strength
C) Composite beam
D) Tapered beam
Ans: B
Detail: Section varies with BM.
287. A material that shows large deformation before fracture is
A) Brittle
B) Ductile
C) Hard
D) Tough
Ans: B
Detail: High ductility.
288. Stress concentration is maximum at
A) Smooth surface
B) Sharp corner
C) Fillet
D) Taper
Ans: B
Detail: Sudden geometry change.
289. The stiffness of a spring is
A) Load × deflection
B) Deflection / load
C) Load / deflection
D) Stress / strain
Ans: C
Detail: k = P/δ.
290. A long column made of brittle material should be designed based on
A) Crushing stress
B) Yield stress
C) Buckling stress
D) Proof stress
Ans: C
Detail: Stability governs.
291. The bending equation assumes
A) Material is elastic
B) Plane sections remain plane
C) Hooke’s law is valid
D) All of the above
Ans: D
Detail: Fundamental assumptions.
292. A beam of constant cross-section but varying moment is
A) Uniform strength beam
B) Non-uniform strength beam
C) Composite beam
D) Tapered beam
Ans: B
Detail: Stress varies.
293. Maximum bending stress varies with
A) Bending moment
B) Area
C) Length
D) Density
Ans: A
Detail: σ = My/I.
294. A bar under axial load and bending experiences
A) Uniform stress
B) Only tensile stress
C) Combined stress
D) Only shear stress
Ans: C
Detail: σ = P/A ± My/I.
295. A shaft is safest in torsion when it is
A) Solid
B) Hollow
C) Stepped
D) Tapered
Ans: B
Detail: Best strength-weight ratio.
296. The product of inertia is zero when
A) Axes are principal
B) Section is unsymmetrical
C) Load is vertical
D) Stress is zero
Ans: A
Detail: Definition of principal axes.
297. A beam of equal strength has
A) Constant I
B) Constant Z
C) Variable Z
D) Constant area
Ans: B
Detail: σ = M/Z = constant.
298. A perfectly plastic material has
A) Infinite E
B) Zero yield stress
C) Constant stress after yield
D) No strain
Ans: C
Detail: Ideal plastic behavior.
299. The most dangerous type of loading is
A) Gradual loading
B) Sudden loading
C) Impact loading
D) Static loading
Ans: C
Detail: Causes maximum stress.
300. The safest design for ductile materials under combined loading uses
A) Rankine theory
B) Tresca theory
C) Von Mises theory
D) Coulomb theory
Ans: C
Detail: Distortion energy theory.