WTMA Springs and Elasticity 4 — Questions and Answers
Question 1: A vehicle suspension spring supports 800 lbs and compresses 4 inches. What is its spring constant?
- 100 lb/in
- 200 lb/in (Correct answer)
- 400 lb/in
- 3,200 lb/in
Correct answer: 200 lb/in
Spring constant k = F/x = 800 lb / 4 in = 200 lb/in.
Question 2: Which type of spring stores energy primarily through twisting rather than bending or compressing?
- Compression spring
- Extension spring
- Torsion spring (Correct answer)
- Leaf spring
Correct answer: Torsion spring
A torsion spring stores energy by twisting along its axis, as seen in clothespins and mousetrap mechanisms.
Question 3: A leaf spring in a heavy truck absorbs road shock primarily by:
- Twisting along its length
- Bending along its arc (Correct answer)
- Compressing its coils
- Stretching like a rubber band
Correct answer: Bending along its arc
Leaf springs are flat, layered metal strips that deflect by bending in an arc to absorb road shock.
Question 4: Engine valve springs must snap the valve shut quickly. They should have:
- Low spring constant and many coils
- High spring constant with appropriate preload (Correct answer)
- Many coils and large diameter only
- Soft wire material for quiet operation
Correct answer: High spring constant with appropriate preload
Valve springs need high stiffness and preload to close reliably at high RPM without bouncing.
Question 5: What is 'spring preload'?
- The maximum load a spring can safely carry
- Initial compression applied before any operating load (Correct answer)
- The spring's free (natural) length
- The weight of the spring itself
Correct answer: Initial compression applied before any operating load
Preload is the compression (or extension) built into a spring assembly before the working load is applied, eliminating slack and controlling initial force.
Question 6: A spring-loaded latch releases when pulled with 5 lbs. The spring compresses 0.5 inches to trip the latch. What is the spring constant?
- 0.1 lb/in
- 2.5 lb/in
- 5 lb/in
- 10 lb/in (Correct answer)
Correct answer: 10 lb/in
k = F/x = 5 lb / 0.5 in = 10 lb/in.
Question 7: Which spring arrangement is most commonly used inside a mattress to spread body weight evenly across the surface?
- A single large spring
- Springs in series (end-to-end)
- Springs in parallel (side-by-side) (Correct answer)
- Torsion springs in a chain
Correct answer: Springs in parallel (side-by-side)
Parallel springs each carry a share of the load independently, distributing pressure across a wide area.
WTMA Springs and Elasticity 4
A vehicle suspension spring supports 800 lbs and compresses 4 inches.
What is its spring constant?