If you are prepping for a mechanical aptitude test and just hit a spring question you couldn’t reason through, here is the good news: almost every spring item on a mechanical aptitude or mechanical comprehension test can be solved with four simple rules and zero calculator. Spring questions show up on the Bennett Mechanical Comprehension Test™ (BMCT), the Wiesen Test of Mechanical Aptitude™ (WTMA), the Ramsay Mechanical Aptitude Test™, the ASVAB Mechanical Comprehension section, and apprenticeship exams like the EIAT™. On MechanicalAptitudeTest.org™ we’ve built and drilled hundreds of these, and the pattern is clear.
Here’s the honest expectation most prep sites won’t set for you: the real test items are mostly pictorial ranking questions — “which spring stretches more,” “which setup drops the load farther” — not spring-constant algebra. You rarely need Hooke’s law. This page teaches the reasoning shortcuts first, walks you through worked examples with real diagrams, and lets you try a free practice drill so you can pattern-match against the format that actually appears.
Not affiliated with or endorsed by any test publisher. Unofficial practice material — original simulated questions only.
The 4 rules that solve almost every spring question
Memorize these four ideas and you can reason through the large majority of spring items on sight — no formula, no arithmetic. They are exactly what the pictorial “which one moves more” items are testing.
Rule 1: Stretch is proportional to the load
A spring stretches in direct proportion to the force pulling on it. Double the weight, double the stretch. Triple the weight, triple the stretch. So if two identical springs hang side by side and one carries twice the load, its block hangs about twice as far down. You never need a number for this — you just compare the loads.
Rule 2: A stiffer spring stretches less under the same load
Under the same pull, a stiffer spring moves less and a softer spring moves more. What makes a coil spring stiffer? Thicker wire, narrower coils, and fewer coils (a shorter spring). So of two otherwise-identical springs, the one wound from thin wire, or with wide coils, or that is simply longer, is the softer one — and it stretches farther.
Rule 3: Springs in series add up their stretch (the chain is softer)
When springs are hooked end to end into a chain (in series), the full load pulls through every spring, so each one stretches its full amount and the stretches add up. Two identical springs in a chain stretch twice as far as one. Series always makes the combination softer.
Rule 4: Springs in parallel split the load (the pair is stiffer and sags less)
When springs sit side by side (in parallel), they share the load. Two identical parallel springs each carry half the weight, so each stretches only half as far and the load drops only half the distance. Parallel always makes the support stiffer and lets it hold more before sagging.
A stiffer, shorter, or heavier-wire spring always moves less under the same load. When a question asks “which one stretches (or compresses) more,” find the softer spring — thinner wire, wider or more coils, greater length — and that’s your answer, no math required.
Springs in series vs parallel (the question everyone gets wrong)
This is the single spring concept candidates most often trip on. Get the two setups straight and you’ll bank the points others lose.
Series: same force through each spring, stretches add
Hook two springs end to end and hang 20 lb from the bottom. That full 20 lb pulls through both springs — neither one carries less. So each stretches the same amount it would alone, and the two stretches add: the chain drops twice as far as a single spring would. Series = softer.
Parallel: load splits between springs, each stretches less
Now hang a 40 lb part from two identical springs standing side by side, joined by a bar. The springs share the weight: each carries 20 lb, so each stretches only half as far, and the part drops half the distance it would on one spring. Parallel = stiffer.
20 lb through a 2-spring chain
Each spring feels the full 20 lb → stretches add → chain drops 2× as far. Softer.
40 lb across 2 springs
Each spring carries 20 lb → each stretches half → part drops half as far. Stiffer.
Which arrangement holds more weight?
If the test frames it as “which setup sags less” or “holds more before bottoming out,” the answer is parallel. Side-by-side springs split every pound, so the pair is stiffer, settles less, and supports a heavier load than the same springs chained in series. This is exactly why a trailer or a truck rides on several springs side by side, not one long spring end to end.
Series adds the stretch (end to end → softer, sags more). Parallel splits the load (side by side → stiffer, holds more, sags less). If you remember only one thing about springs, remember this pair.
A minority of items (and some ASVAB/EIAT math-style questions) hand you a spring constant. Then you can use Hooke’s law: F = k × x (force = stiffness × stretch).
In series, the stretches add for the same force. In parallel, the springs share the force but stretch the same amount, so their stiffnesses add. If no number appears in the question, skip the formula — the picture already tells you the answer.
Worked spring examples (with diagrams)
These are the formats you’ll actually see. Each one is a simulated, style-matched question — not actual test content. Read the stem, pick your answer, then open the reveal to check your reasoning against the rule it uses.
Two identical springs, A and B, hang side by side from the same beam. A 10-pound block hangs from spring A and a 20-pound block hangs from spring B. Which block hangs lower?
A. The block on spring B B. The block on spring A C. Both hang at the same height
Show the answer & how to get it
Answer: A. Rule 1 in action: identical springs stretch in proportion to the load. The 20-pound block pulls with twice the force of the 10-pound block, so spring B stretches about twice as far and its block ends up lower. Both springs start at the same length from the same beam, so the extra stretch of the heavier-loaded spring decides it.
Springs A and B have the same coil diameter, free length, and number of coils, and are made of the same steel. Spring A is wound from 1/4-inch wire and spring B from 1/8-inch wire. A 15-pound weight is hung from each. Which spring stretches farther?
A. Spring A, with the thick wire B. Spring B, with the thin wire C. Both stretch the same amount
Show the answer & how to get it
Answer: B. Rule 2: thicker wire is much harder to flex, so the heavy-wire spring is stiffer and the thin-wire spring is softer. Under the same 15-pound pull, the softer thin-wire spring gives more and stretches farther. This is why heavy-duty springs are wound from noticeably fatter wire.
Arrangement 1 is a single spring. Arrangement 2 is two identical springs hooked end to end into a chain, hung from the same beam. A 20-pound weight is hung from each. Compared with the single spring, the total stretch of the two-spring chain is:
A. Half as much B. The same C. Twice as much
Show the answer & how to get it
Answer: C. Rule 3: the full 20 pounds pulls through every part of the chain, so each spring feels the entire load and stretches just as much as the single spring does. With two springs each stretching that full amount, the stretches add and the chain extends twice as far. Connecting springs end to end (series) always makes the combination softer.
A 40-pound part is hung two ways. Setup 1 uses a single spring. Setup 2 uses two of the same springs side by side, joined by a bar so they share the load equally. In which setup does the part drop farther?
A. Setup 1, with one spring B. Setup 2, with two springs C. The part drops the same in both
Show the answer & how to get it
Answer: A. Rule 4: side-by-side springs split the load, so in Setup 2 each spring carries only half of the 40 pounds and stretches only half as far. The part drops the most in Setup 1, where the single spring must carry all 40 pounds by itself. Adding springs in parallel makes the support stiffer.
Spring A stretches 1 inch for every 10 pounds of pull; spring B stretches 1/2 inch for every 10 pounds. The two are hooked end to end, A on top, and a 10-pound weight hangs from the bottom. What is the total stretch of the chain?
A. 3/4 inch B. 1 inch C. 1-1/2 inches
Show the answer & how to get it
Answer: C. This is a series chain (Rule 3) with numbers. The full 10-pound pull passes through both springs, so spring A stretches its full 1 inch and spring B stretches its full 1/2 inch. In series the stretches add: 1 + 1/2 = 1-1/2 inches. Notice you didn’t need Hooke’s law — just “series stretches add.”
Compression, extension, and torsion springs — what to notice
Some items just ask you to identify a spring by how it’s loaded. Three types cover everything you’ll see:
- Compression springs push back when squeezed — car suspension, engine valve springs, a click pen. Open gaps between the coils leave room to compress. The more you squeeze one, the harder it pushes.
- Extension springs pull back when stretched — screen-door springs, hanging spring scales. They have a hook at each end and coils that sit closed together at rest. The more you stretch one, the harder it pulls.
- Torsion springs twist — a clothespin, a garage-door spring on a rotating shaft, a mousetrap. They store energy by winding tighter around their axis, not by changing length.
The reasoning tie-in matters more than the labels: a compression spring pushes harder the more it’s compressed, and an extension spring pulls harder the more it’s stretched. That’s why a screen door snaps shut faster from wide open than from barely cracked — the spring is stretched more, so its pull is stronger.
Common spring-question traps (and how to dodge them)
How spring questions fit the rest of the mechanical test
Springs are one member of the “simple-machine reasoning” family. The same “compare two setups” logic runs through gears, pulleys, and levers — and the same named tests lean on all four. Drill them together and the whole mechanical section gets easier.
| Question type | What it tests | Where it shows up |
|---|---|---|
| Gears | Turn direction, speed & torque from tooth counts | Bennett, Wiesen, Ramsay, ASVAB MC |
| Pulleys | Mechanical advantage, load sharing, direction of pull | Bennett, Wiesen, Ramsay, ASVAB MC |
| Levers | Effort vs load across a pivot, balance points | Bennett, Wiesen, Ramsay, ASVAB MC |
| Springs | Stretch vs load, stiffness, series vs parallel | Bennett, Wiesen, Ramsay, ASVAB MC |
Ready to see them in the exact test formats? Browse more sample questions, or go straight to a full-length practice run for the Bennett BMCT, Wiesen WTMA, or Ramsay MAT. You can also take the full mechanical aptitude practice test.
Try it free: practice spring questions the way they’re really asked
These are pictorial ranking questions with instant explanations — the same style you’ll meet on test day. No email required. Answer a few, then check your reasoning against the four rules above.
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Spring questions FAQ
Do I need to know Hooke’s law for the mechanical aptitude test?
Usually no. Most spring items are pictorial ranking questions — “which stretches more,” “which drops farther” — that you solve by comparing loads and stiffness. Only a minority of items give you numbers; for those, Hooke’s law (F = k × x) helps. If a question has no numbers, skip the formula.
What is the difference between springs in series and springs in parallel?
Series means springs are hooked end to end; the full load pulls through each one, so their stretches add and the chain is softer. Parallel means springs sit side by side; they share the load, so each stretches less and the pair is stiffer. End to end stretches more; side by side stretches less.
Which spring arrangement holds more weight — series or parallel?
Parallel. Side-by-side springs split every pound between them, so the combination is stiffer, sags less, and supports more weight before bottoming out. That’s why suspensions use several springs side by side rather than one long spring chained end to end.
Why does a stiffer spring stretch less than a softer one?
Stiffness is how strongly a spring resists being deformed. Under the same load, a stiffer spring gives less, so it stretches (or compresses) less. Thicker wire, narrower coils, and fewer or shorter coils all make a spring stiffer — and therefore move less under the same pull.
How do I answer a spring question without a calculator?
Use the four rules: stretch is proportional to load, a stiffer spring stretches less, series adds the stretch, and parallel splits the load. Identify the load on each spring and which spring is softer, then pick the one that moves more or less as the question asks. No arithmetic needed for most items.
Where do spring questions show up on mechanical aptitude tests?
Spring items appear on the Bennett Mechanical Comprehension Test, the Wiesen Test of Mechanical Aptitude, the Ramsay Mechanical Aptitude Test, the ASVAB Mechanical Comprehension section, and apprenticeship exams such as the EIAT. They usually sit alongside gears, pulleys, and levers as part of the mechanical-reasoning section.
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