Bennett Mechanical Test Springs and Elasticity 2 — Questions and Answers
Question 1: A spring is stretched beyond its elastic limit. What happens when the force is removed?
- It returns to its original length
- It becomes permanently deformed (Correct answer)
- It becomes stiffer than before
- It breaks immediately
Correct answer: It becomes permanently deformed
Beyond the elastic limit, the spring undergoes plastic deformation and cannot fully recover its original shape when the force is removed.
Question 2: A spring with constant 100 N/m stores 50 J of elastic potential energy. How far is it compressed?
- 0.5 m
- 1 m (Correct answer)
- 2 m
- 0.25 m
Correct answer: 1 m
Using PE = ½kx²: 50 = ½(100)x², so x² = 1 and x = 1 m.
Question 3: A stiffer spring has a _____ spring constant.
- Lower
- Higher (Correct answer)
- Variable
- Negative
Correct answer: Higher
A higher spring constant means more force is required per unit of displacement, which is the definition of a stiffer spring.
Question 4: What happens to the period of oscillation of a mass on a spring if the mass is increased?
- Period decreases
- Period increases (Correct answer)
- Period stays the same
- Period becomes unpredictable
Correct answer: Period increases
Period T = 2π√(m/k), so increasing mass increases the period, meaning the oscillation slows down.
Question 5: A spring with a constant of 200 N/m is stretched 5 cm (0.05 m). What is the restoring force?
- 4000 N
- 0.025 N
- 10 N (Correct answer)
- 4 N
Correct answer: 10 N
Using F = kx: F = 200 N/m × 0.05 m = 10 N.
Question 6: Which type of spring stores energy primarily through twisting rather than compression or extension?
- Compression spring
- Extension spring
- Torsion spring (Correct answer)
- Constant force spring
Correct answer: Torsion spring
A torsion spring stores elastic energy by being twisted about its axis, commonly used in clothespins and mouse traps.
Question 7: Rubber bands demonstrate elastic behavior because they:
- Cannot be stretched at all
- Break when stretched slightly
- Return to their original shape after stretching (Correct answer)
- Permanently deform when stretched
Correct answer: Return to their original shape after stretching
Rubber bands exhibit elasticity because they recover their original shape after the stretching force is removed, within their elastic limit.
Bennett Mechanical Test Springs and Elasticity 2
A spring is stretched beyond its elastic limit.
What happens when the force is removed?