NCERT Physics Class 11 Exemplar Ch 9 Mechanical Properties of Solids Part 2

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One and More then Answer

Q.9 The stress-strain graphs for two materials are shown in Fig. (assume same scale).

Tensile strength

Tensile Strength

(a) Material (ii) is more elastic than material (i) and hence material (ii) is more brittle.

(b) Material (i) and (ii) have the same elasticity and the same brittleness.

(c) Material (ii) is elastic over a larger region of strain as compared to (i).

(d) Material (ii) is more brittle than material (i).

Answer: (c), (d)

Q.10 A wire is suspended from the ceiling and stretched under the action of a weight F suspended from its other end. The force exerted by the ceiling on it is equal and opposite to the weight.

(a) Tensile stress at any cross-section A of the wire is F/A.

(b) Tensile stress at any cross section is zero.

(c) Tensile stress at any cross-section A of the wire is 2F/A.

(d) Tension at any cross-section A of the wire is F.

Answer: (a), (d)

Q.11 A rod of length l and negligible mass is suspended at its two ends by two wires of steel (wire A) and aluminum (wire B) of equal lengths (Fig.). The cross-sectional areas of wires A and B are , respectively.

Rod with steel wires

Rod with Steel Wires

(a) Mass m should be suspended close to wire A to have equal stresses in both the wires.

(b) Mass m should be suspended close to B to have equal stresses in both the wires.

(c) Mass m should be suspended at the middle of the wires to have equal stresses in both the wires.

(d) Mass m should be suspended close to wire A to have equal strain in both wires.

Answer: (b), (d)

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