CBSE Class 11 Physics Mechanical Properties Of Solids Assignment

Question. The stress-strain curves are drawn for two different materials X and Y. It is observed that the ultimate strength point and the fracture point are close to each other for material X but are far apart for material Y. We can say that materials X and Y are likely to be (respectively)
(a) ductile and brittle
(b) brittle and ductile
(c) brittle and plastic
(d) plastic and ductile
Answer. B

Question. When a block of mass M is suspended by a long wire of length L, the length of the wire becomes (L + l).
The elastic potential energy stored in the extended wire is
(a) 1/2 MgL
(b) Mgl
(c) MgL
(d) 1/2 Mgl
Answer. D

Question. Two wires are made of the same material and have the same volume. The first wire has cross-sectional area A and the second wire has cross-sectional area 3A. If the length of the first wire is increased by Dl on applying a force F, how much force is needed to stretch the second wire by the same amount?
(a) 9F
(b) 6F
(c) 4F
(d) F
Answer. C

Question. The bulk modulus of a spherical object is ‘B’. If it is subjected to uniform pressure ‘p’, the fractional decrease in radius is
(a) B/3p
(b) 3/pB
(c) p/3B
(d) p/B
Answer. C

Question. The Young’s modulus of steel is twice that of brass.Two wires of same length and of same area of cross section, one of 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) 4 : 1
(b) 1 : 1
(c) 1 : 2
(d) 2 : 1
Answer. D

Question. The approximate depth of an ocean is 2700 m.The compressibility of water is 45.4 × 10^–11 Pa^–1 and density of water is 103 kg/m³. What fractional compression of water will be obtained at the bottom of the ocean?
(a) 1.2 × 10^–2
(b) 1.4 × 10^–2
(c) 0.8 × 10^–2
(d) 1.0 × 10^–2
Answer. A

Question. Copper of fixed volume V is drawn into wire of length l. When this wire is subjected to a constant force F, the extension produced in the wire is Dl.Which of the following graphs is a straight line?
(a) Δl versus 1/l
(b) Δl versus l 2
(c) Δl versus 1/l 2
(d) Δl versus l
Answer. B

Question. The following four wires are made of the same material. Which of these will have the largest extension when the same tension is applied?
(a) length = 200 cm, diameter = 2 mm
(b) length = 300 cm, diameter = 3 mm
(c) length = 50 cm, diameter = 0.5 mm
(d) length = 100 cm, diameter = 1 mm
Answer. C