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8
MCQ (Single Correct Answer)

Consider two cylindrical rods of identical dimensions, one of 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
Both the rods will elongate but there shall be no perceptible change in shape
B
The steel rod will elongate and change shape but the rubber rod will only elongate
C
The steel rod will elongate without any perceptible change in shape, but the rubber rod will elongate and the shape of the bottom edge will change to an ellipse
D
The steel rod will elongate, without any perceptible change in shape, but the rubber rod will elongate with the shape of the bottom edge tapered to a tip at the centre
9
MCQ (Multiple Correct Answer)

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

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)
10
MCQ (Multiple Correct Answer)

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 its 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 $2 F / A$
D
Tension at any cross-section $A$ of the wire is $F$
11
MCQ (Multiple Correct Answer)

A rod of length I and negligible mass is suspended at its two ends by two wires of steel (wire $A$ ) and aluminium (wire $B$ ) of equal lengths (figure). The cross-sectional areas of wires $A$ and $B$ are $1.0 \mathrm{~mm}^2$ and $2.0 \mathrm{~mm}^2$, respectively.

$\left(Y_{\mathrm{Al}}=70 \times 10^9 \mathrm{Nm}^{-2}\right.$ and $\left.Y_{\text {steel }}=200 \times 10^9 \mathrm{Nm}^{-2}\right)$

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
12
MCQ (Multiple Correct Answer)

For an ideal liquid,

A
the bulk modulus is infinite
B
the bulk modulus is zero
C
the shear modulus is infinite
D
the shear modulus is zero