NEET Physics Mechanical Properties of Solids MCQs Set 01

Question. The maximum load a wire can with stand without breaking, when its length is reduced to half of its original length, will
(a) remain same
(b) be four times
(c) be half
(d) be double

Answer: A

Question. The temperature of a wire is doubled. The Young's modulus of elasticity
(a) will decrease
(b) will become four times
(c) will also double
(d) will remain same

Answer: A

Question. A spring is stretched by applying a load to its free end. The strain produced in the spring is
(a) longitudinal and shear
(b) volumetric
(c) shear
(d) longitudinal

Answer: A

Question.  Consider two cylindrical rods of identical dimensions, oneof rubber and the other of steel. Both the rods are fixed rigidly at one end to the roof. A mass M is attached to each of the free ends at the centre of the rods.
(a) The steel rod will elongate, without any perceptible changein shape, but the rubber rod will elongate with the shape of the bottom edge tapered to a tip at the centre
(b) The steel rod will elongate without any perceptible change in shape, but the rubber rod will elongate andthe shape of the bottom edge will change to an ellipse
(c) The steel rod will elongate and change shape but the rubber rod will only elongate
(d) Both the rods will elongate but there shall be no perceptible change in shape

Answer: A

Question.  A wire is stretched by 1 kg wt. If the radius of the wire is doubled, its Young's modulus will be
(a) remains unchanged
(b) become doubled
(c) becomes half
(d) become four times

Answer: A

Question.  The Young's modulus of steel is twice that of brass. Twowires of same length and of same area of cross section, oneof steel and another of brass are suspended from the same roof. If we want the lower ends of the wires to be at the same level, then the weights added to the steel and brass wires must be in the ratio of :
(a) 2 : 1
(b) 4 : 1
(c) 1 : 1
(d) 1 : 2

Answer: A

Question.  An iron rod of length 2m and cross-sectional area of 50 mm² stretched by 0.5 mm, when a mass of 250 kg is hung from its lower end. Young’s modulus of iron rod is
(a) 19.6 × 10¹⁰ N/m²
(b) 19.6 × 10²⁰ N/m²
(c) 19.6 × 10¹⁸ N/m²
(d) None of these

Answer: A

Question. Assertion: Solids are least compressible and gases are most compressible.
Reason: solids have definite shape and volume but gasesdo not have either definite shape or definite volume.
(a) If both Assertion and Reason are correct, but Reason is not the correct explanation of Assertion
(b) If Assertion is correct but Reason is incorrect
(c) If both the Assertion and Reason are incorrect
(d) If both Assertion and Reason are correct and Reason is the correct explanation of Assertion

Answer: A

Question.  The fractional change in volume of a glass slab when subjected to a hydraulic pressure of 10 atm is: [Bulk modulus of glass = 37 × 10⁹ N/m²]
(a) 2.74 × 10^–5
(b) 8.31 × 10^–4
(c) 5.12 × 10^–3
(d) 6.11 × 10^–4

Answer: A

Question.  A body of mass 10 kg is attached to a wire of radius 3 cm. It’s breaking stress is 4.8 × 10⁷ Nm^–2, the area of crosssectionof the wire is 10^–6 m². What is the maximum angular velocity with which it can be rotated in the horizontal circle ?
(a) 4 rad sec^–1
(b) 1 rad sec^–1
(c) 2 rad sec^–1
(d) 8 rad sec^–1

Answer: A

Question.  A copper wire of length 1.0 m and a steel wire of length 0.5 m having equal cross-sectional areas are joined end to end. The composite wire is stretched by a certain load which stretches the copper wire by 1 mm. If the Young’s modulii of copper and steel are respectively 1.0 × 10¹¹ Nm^–2 and 2.0 × 10¹¹ Nm^–2, the total extension of the composite wire is
(a) 1.25 mm
(b) 1.50 mm
(c) 2.0 mm
(d) 1.75 mm

Answer: A

Question. A uniform wire (Young’s modulus 2 × 10¹¹ Nm^–2) is subjected to longitudinal tensile stress of 5 × 10⁷ Nm^–2. If the overall volume change in the wire is 0.02%, the fractional decrease in the radius of the wire is close to
(a) 0.25 × 10^–4
(b) 1.0 × 10^–4
(c) 1.5 × 10^–4
(d) None of these

Answer: A

Question.  A uniform cube is subjected to volume compression. If each side is decreased by 1%, then bulk strain is
(a) None of these
(b) 0.02
(c) 0.06
(d) 0.01

Answer: A