Bennett Mechanical Test Springs and Elasticity 1 — Questions and Answers
Question 1: According to Hooke's Law, when the force applied to a spring is doubled, what happens to its extension?
- It stays the same
- It doubles (Correct answer)
- It quadruples
- It halves
Correct answer: It doubles
Hooke's Law states that extension is directly proportional to applied force (F = kx), so doubling the force doubles the extension.
Question 2: A spring has a spring constant of 50 N/m. How much force is needed to stretch it 0.2 meters?
- 250 N
- 10 N (Correct answer)
- 0.004 N
- 100 N
Correct answer: 10 N
Using F = kx: F = 50 N/m × 0.2 m = 10 N.
Question 3: Two identical springs connected in series (end to end) will have what effective spring constant compared to one spring?
- Twice as stiff
- Four times as stiff
- Half as stiff (Correct answer)
- The same stiffness
Correct answer: Half as stiff
Springs in series share the same force, but each stretches, so total extension doubles and effective spring constant is halved.
Question 4: What is the SI unit of the spring constant?
- Newtons (N)
- Joules (J)
- Newtons per meter (N/m) (Correct answer)
- Meters per Newton (m/N)
Correct answer: Newtons per meter (N/m)
Spring constant k = F/x, so its unit is force divided by distance, which is Newtons per meter (N/m).
Question 5: Which material property describes a material's ability to return to its original shape after being deformed?
- Plasticity
- Elasticity (Correct answer)
- Ductility
- Brittleness
Correct answer: Elasticity
Elasticity is the property that allows a material to recover its original shape and size after the deforming force is removed.
Question 6: The elastic potential energy stored in a spring with spring constant k compressed by distance x is:
- kx
- ½kx² (Correct answer)
- kx²
- 2kx
Correct answer: ½kx²
The potential energy stored in a spring is PE = ½kx², derived from integrating the force over the displacement.
Question 7: When two identical springs are connected in parallel (side by side, sharing the same endpoints), the effective spring constant is:
- Half the single spring constant
- The same as a single spring
- Twice the single spring constant (Correct answer)
- Four times the single spring constant
Correct answer: Twice the single spring constant
Springs in parallel each share the load and deflect equally, so their spring constants add together, giving twice the stiffness.
Bennett Mechanical Test Springs and Elasticity 1
According to Hooke's Law, when the force applied to a spring is doubled, what happens to its extension?