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Question
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.
Options
Both the rods will elongate but there shall be no perceptible change in shape.
The steel rod will elongate and change shape but the rubber rod will only elongate.
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.
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.
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Solution
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.
Explanation:
Consider the diagram. A mass M is attached at the centre. As the mass is connected to both the rods, both rod will be elongated, but due to different elastic properties of the material rubber changes shape.
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