Question
A metal wire is stretched. The wire obeys Hooke’s law.
Which quantity has a value that does not change?
A extension
B strain
C stress
D Young modulus
Answer/Explanation
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Question
A metal wire, of cross-sectional area A and unstretched length l, is subjected to stress σ. As a result it has strain ε.
Which expression gives the Young modulus of the metal?
Answer/Explanation
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Question
The spring constants of four springs are determined by plotting the following graphs of force F
against extension x.
Which order of the graphs shows decreasing spring constants?
A 2 → 1 → 3 → 4
B 3 → 4 → 2 → 1
C 4 → 2 → 1 → 3
D 4 → 3 → 2 → 1
Answer/Explanation
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Question
A wire of circular cross-section, which obeys Hooke’s law, is used to suspend a basket as shown.
The Young modulus for the material of the wire is \(2.5 \times 10^{11}\)Pa.
When a weight of 34 N is added to the basket, the strain in the wire increases by \(6.0 \times 10^{–5}\).
What is the radius of the wire?
A \(7.2 \times 10^{–7}\) m B \(2.3 \times 10^{–6}\) m C \(8.5 \times 10^{–4}\) m D \(1.7 \times 10^{–3}\) m
Answer/Explanation
Question
A composite rod is made by attaching a glass-reinforced plastic rod and a nylon rod end to end, as shown.
The rods have the same cross-sectional area and each rod is 1.00 m in length. The Young modulus Ep of the plastic is 40GPa and the Young modulus En of the nylon is 2.0GPa.
The composite rod will break when its total extension reaches 3.0 mm.
What is the greatest tensile stress that can be applied to the composite rod before it breaks?
A 2.9 × 106Pa
B 5.7 × 106Pa
C 2.9 × 109Pa
D 5.7 × 109Pa
Answer/Explanation
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