Pulley Questions on Mechanical Aptitude Tests

Almost everyone who gets these wrong makes the same mistake, and it is not the arithmetic. They count pulleys. The rule counts rope.

Mechanical aptitude tests ask about pulleys because a pulley system shows, in one picture, whether you understand that a machine trades force for distance. There is no way to fake it and no formula sheet to memorise — but there is exactly one rule you need, and it is not the one most people carry into the exam.

The rule: the effort you need is the load divided by the number of rope segments that support the moving block. Not the number of pulleys. Not the number of wheels you can see. The number of rope segments actually pulling up on the load.

Why that is the rule: the load hangs from several strands of the same rope, and one rope under tension pulls with the same force everywhere along its length. If four strands share a 160 kg load, each strand carries 40 kg — so you only have to pull with 40 kg. The rope does not care how many wheels it went around on the way.

And the price: whatever you divide the force by, you multiply the distance by. Lifting that 160 kg load one metre means pulling four metres of rope. A machine never gives you something for nothing; it only lets you pay in a different currency. If a question asks how far you must pull, this is the half people forget.

Practise the rest of the mechanics

Pulleys are one of five areas these tests draw on. The full paper adds gears, levers, ramps and hydraulics, timed, with the same explained answers.

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The rule, and the trap

Eight worked pulley questions

8 questions

1. Find the load, and look only at the strands that pull upward on the moving block. Ignore the strand you hold if it runs down from a fixed pulley — that one changes direction, it does not support the load.

2. Count those strands. Call it n.

3. Effort = load ÷ n. Distance pulled = height lifted × n.

4. Sanity-check the direction: more pulleys should mean less force and more rope. If your answer needs more force than the bare load, you have inverted something.

One more habit worth building: before you compute, guess whether the answer should be bigger or smaller than the load. Most wrong options on these tests are the load itself, double it, or the result of dividing by the pulley count instead of the segment count — all of which you can eliminate by direction alone.

How it is asked: These appear as "what force is needed", "what is the mechanical advantage", or "how much rope must be pulled". All three are the same rule asked from different ends.

Question 1

A 50 kg load hangs from a single fixed pulley bolted to the ceiling. Ignoring friction and the weight of the rope, how much force must you pull with to lift the load?

  1. A12.5 kg of force
  2. B25 kg of force
  3. C50 kg of force
  4. D100 kg of force
▶Explanation

Answer: C. 50 kg of force

🐱 Count the rope segments that actually carry the load, not the pulleys. A fixed pulley changes the direction of your pull and nothing else: one segment carries the load, so you still pull the full 50 kg. The classic mistake is counting pulleys instead of segments — a fixed pulley adds no mechanical advantage at all, however many you bolt to the ceiling.

Question 2

An 80 kg load hangs from 1 movable pulley hanging in the rope, with a fixed pulley above. Ignoring friction and the weight of the rope, how much force must you pull with to lift the load?

  1. A10 kg of force
  2. B20 kg of force
  3. C40 kg of force
  4. D80 kg of force
▶Explanation

Answer: C. 40 kg of force

🐱 Count the rope segments that actually carry the load, not the pulleys. Each movable pulley is held up by 2 segments, so 1 movable pulley gives 2 load-bearing segments. 80 ÷ 2 = 40 kg. The classic mistake is counting pulleys instead of segments — a fixed pulley adds no mechanical advantage at all, however many you bolt to the ceiling.

Question 3

A 160 kg load hangs from 2 movable pulleys hanging in the rope, with a fixed pulley above. Ignoring friction and the weight of the rope, how much force must you pull with to lift the load?

  1. A32 kg of force
  2. B40 kg of force
  3. C80 kg of force
  4. D160 kg of force
▶Explanation

Answer: B. 40 kg of force

🐱 Count the rope segments that actually carry the load, not the pulleys. Each movable pulley is held up by 2 segments, so 2 movable pulleys give 4 load-bearing segments. 160 ÷ 4 = 40 kg. The classic mistake is counting pulleys instead of segments — a fixed pulley adds no mechanical advantage at all, however many you bolt to the ceiling.

Question 4

A 160 kg load hangs from 4 movable pulleys hanging in the rope, with a fixed pulley above. Ignoring friction and the weight of the rope, how much force must you pull with to lift the load?

  1. A16 kg of force
  2. B20 kg of force
  3. C40 kg of force
  4. D160 kg of force
▶Explanation

Answer: B. 20 kg of force

🐱 Count the rope segments that actually carry the load, not the pulleys. Each movable pulley is held up by 2 segments, so 4 movable pulleys give 8 load-bearing segments. 160 ÷ 8 = 20 kg. The classic mistake is counting pulleys instead of segments — a fixed pulley adds no mechanical advantage at all, however many you bolt to the ceiling.

Question 5

A 240 kg load hangs from 2 movable pulleys hanging in the rope, with a fixed pulley above. Ignoring friction and the weight of the rope, how much force must you pull with to lift the load?

  1. A60 kg of force
  2. B80 kg of force
  3. C120 kg of force
  4. D240 kg of force
▶Explanation

Answer: A. 60 kg of force

🐱 Count the rope segments that actually carry the load, not the pulleys. Each movable pulley is held up by 2 segments, so 2 movable pulleys give 4 load-bearing segments. 240 ÷ 4 = 60 kg. The classic mistake is counting pulleys instead of segments — a fixed pulley adds no mechanical advantage at all, however many you bolt to the ceiling.

Question 6

A 120 kg load hangs from 3 movable pulleys hanging in the rope, with a fixed pulley above. Ignoring friction and the weight of the rope, how much force must you pull with to lift the load?

  1. A20 kg of force
  2. B24 kg of force
  3. C40 kg of force
  4. D120 kg of force
▶Explanation

Answer: A. 20 kg of force

🐱 Count the rope segments that actually carry the load, not the pulleys. Each movable pulley is held up by 2 segments, so 3 movable pulleys give 6 load-bearing segments. 120 ÷ 6 = 20 kg. The classic mistake is counting pulleys instead of segments — a fixed pulley adds no mechanical advantage at all, however many you bolt to the ceiling.

Question 7

A 200 kg load hangs from 2 movable pulleys hanging in the rope, with a fixed pulley above. Ignoring friction and the weight of the rope, how much force must you pull with to lift the load?

  1. A12.5 kg of force
  2. B25 kg of force
  3. C40 kg of force
  4. D50 kg of force
▶Explanation

Answer: D. 50 kg of force

🐱 Count the rope segments that actually carry the load, not the pulleys. Each movable pulley is held up by 2 segments, so 2 movable pulleys give 4 load-bearing segments. 200 ÷ 4 = 50 kg. The classic mistake is counting pulleys instead of segments — a fixed pulley adds no mechanical advantage at all, however many you bolt to the ceiling.

Question 8

An 180 kg load hangs from 3 movable pulleys hanging in the rope, with a fixed pulley above. Ignoring friction and the weight of the rope, how much force must you pull with to lift the load?

  1. A7.5 kg of force
  2. B15 kg of force
  3. C22.5 kg of force
  4. D30 kg of force
▶Explanation

Answer: D. 30 kg of force

🐱 Count the rope segments that actually carry the load, not the pulleys. Each movable pulley is held up by 2 segments, so 3 movable pulleys give 6 load-bearing segments. 180 ÷ 6 = 30 kg. The classic mistake is counting pulleys instead of segments — a fixed pulley adds no mechanical advantage at all, however many you bolt to the ceiling.

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The one case that catches people out

A single fixed pulley — one bolted to the ceiling, with the rope going over it and down to the load — gives you no mechanical advantage at all. One rope segment supports the load, so the effort equals the load. Lifting 50 kg takes 50 kg of pull.

It is still useful, because it changes the direction of your effort: you pull down, using your body weight, instead of hauling up. That is a real ergonomic gain and no force gain, and test writers love the distinction. If you counted "one pulley, so half the weight," you fell for exactly the trap the question was built around.

A movable pulley is the opposite: it hangs in the rope and rides up with the load, so two segments support it and the effort halves. Two movable pulleys, four segments, a quarter. The pattern is segments, always segments.

How to answer one in under thirty seconds

1. Find the load, and look only at the strands that pull upward on the moving block. Ignore the strand you hold if it runs down from a fixed pulley — that one changes direction, it does not support the load.

2. Count those strands. Call it n.

3. Effort = load ÷ n. Distance pulled = height lifted × n.

4. Sanity-check the direction: more pulleys should mean less force and more rope. If your answer needs more force than the bare load, you have inverted something.

One more habit worth building: before you compute, guess whether the answer should be bigger or smaller than the load. Most wrong options on these tests are the load itself, double it, or the result of dividing by the pulley count instead of the segment count — all of which you can eliminate by direction alone.

Where to go next

Mechanical reasoning test (20 questions, 20 min)The timed paper: gears, pulleys, levers, ramps and hydraulics, with a breakdown by area when you submit.ASVAB subtests, and which of ours matchMechanical Comprehension is one of the ten ASVAB subtests, and it is the one our mechanical paper lines up with most closely.Spatial reasoning testThe other visual paper: rotation, mirroring and folding. Assembling Objects on the ASVAB works the same way.

FAQ

Do I count the pulleys or the rope segments?

The rope segments supporting the moving block. Counting pulleys gives the right answer often enough to feel safe and then fails on exactly the questions designed to separate people — a single fixed pulley gives no advantage at all, and systems that route the rope back over a fixed pulley add a wheel without adding a supporting segment.

Does a fixed pulley reduce the force I need?

No. It redirects your effort so you can pull downwards instead of lifting upwards, which is genuinely easier on your body, but the force is unchanged. One supporting segment means effort equals load.

Why do I have to pull so much more rope?

Because energy is conserved. Force times distance in equals force times distance out, so dividing the force by four multiplies the rope by four. In a real system it is slightly worse than that, since friction and the weight of the moving pulleys take a cut — aptitude tests normally tell you to ignore both.

Are these real exam questions?

No. Every question here is original and generated from the physics itself, then checked at build time — the arithmetic must come out whole and the wrong options must sit on both sides of the right one, so you cannot pick the answer by its position or by it being the tidy number.

PurrLearn is not affiliated with, endorsed by, or connected to any test publisher or assessment provider. Mechanical aptitude tests are produced by a number of different companies under their own names; those names are their trademarks. Nothing on this page is taken from any commercial exam or question bank — the questions are generated from standard mechanics.