A force F stretches a wire and produces an extension l. The energy stored in the wire equals ½Fl only on which condition?
Correct answer D. The extension of the wire is proportional to the force applied
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Physics MCQs
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If the ratio of stress to strain is the Young’s modulus of a material, how is the tension in a wire related to its extension?
Correct answer A. Directly proportional to extension
A wire hanging vertically is stretched by 1 mm when a 20 N weight is hung from its lower end. How much energy does the wire store?
Correct answer C. 0.01 J
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A force applied to one end of an elastic wire produces a strain α. If Y is the Young’s modulus of the wire’s material, how much energy is stored per unit volume of the wire?
Correct answer A. ½Yα²
A wire of length L is stretched by an extension E when a force F is applied at one end. If the elastic limit is not exceeded, how much energy is stored in the wire?
Correct answer C. ½FE
Which of these quantities does not have the dimensions of force per unit area?
Correct answer B. Strain
Which dimensional formula represents stress?
Correct answer D. ML⁻¹T⁻²
Which of these substances has the highest elasticity?
Correct answer D. Steel
By which method can biomass be turned into fuel?
Correct answer C. Both A and B
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Which type of cell converts solar energy directly into electrical energy?
Correct answer B. Photovoltaic
What kind of energy source is geothermal energy?
Correct answer B. Renewable
What kind of force is the propulsion force of a rocket?
Correct answer A. non-conservative force
What does the area under a force-displacement graph represent?
Correct answer C. Work done
A man lifts a 40 kg mass vertically through 1 m in 10 s, while a child lifts a 10 kg mass vertically through 1 m in 1 s. Which conclusion is correct?
Correct answer A. The man does more work than the child
What happens when two protons are pushed closer together?
Correct answer D. P.E. between them increases
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How is the escape velocity v_esc related to the orbital speed v_o close to the Earth’s surface?
Correct answer D. v_esc = √2 v_o
Work has the same dimensions as which of the following quantities?
Correct answer B. Torque
What is one megawatt hour equal to?
Correct answer D. 36 × 10⁸ J
What happens when the speed of a moving body is doubled?
Correct answer C. Its momentum is doubled
What can be said about a formula for the gravitational potential energy of a body?
Correct answer D. It has no general formula