Elastic strain energy Quiz
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5 questions, one answer each
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1. A wire is stretched by 3.0 mm by a force of 60 N within the elastic limit. How much strain energy is stored?
- A. 0.090 J
- B. 0.18 J
- C. 90 J
- D. 0.045 J
2. The extension of a spring that obeys Hooke's law is tripled. By what factor does the stored energy increase?
- A. 3
- B. 6
- C. 9
- D. 27
3. What is represented by the area under a force–extension graph?
- A. The stiffness
- B. The work done, equal to the energy stored
- C. The Young modulus
- D. The yield point
4. A force–extension curve has a decreasing gradient. A student estimates the area with trapezia. How does the estimate compare with the true area?
- A. It is too large
- B. It is exactly right
- C. It is too small
- D. It depends on the number of strips only
5. A spring stores 0.80 J and launches a 0.10 kg trolley with all of this energy. What is the trolley's speed?
- A. 4.0 m s⁻¹
- B. 16 m s⁻¹
- C. 2.8 m s⁻¹
- D. 0.40 m s⁻¹