§-Quick questions
NSWEngineering StudiesPreliminary Module: Lifting Devices
Quick questions on Mechanical advantage in pulley systems: HSC Engineering Studies Lifting Devices
6short Q&A pairs drawn directly from our worked dot-point answer. For full context and worked exam questions, read the parent dot-point page.
What are pulley systems?Show answer
Single fixed pulley. Changes direction only. IMA = 1, VR = 1. Effort equals load.
What is the conservation-of-energy basis?Show answer
Mechanical advantage never creates energy; it trades force for distance. In an ideal system the work in equals the work out, , which rearranges directly to . Once friction is present, some input work becomes heat in the bearings and from rope flexing, so the input work always exceeds the output work, and the shortfall is the efficiency. This is why a clear energy statement is the safest way to check any pulley answer: compute input work and output work separately, and their ratio must equal the stated efficiency.
What is single fixed pulley?Show answer
Changes direction only. IMA = 1, VR = 1. Effort equals load.
What is single movable pulley?Show answer
Two rope segments support the load. IMA = 2, VR = 2. Effort is half the load; rope travels twice the load distance.
What is block and tackle?Show answer
A fixed block and a movable block, each with one or more pulleys. The IMA equals the number of rope segments supporting the load block, not the total number of pulleys.
What is compound pulley?Show answer
Two or more separate block-and-tackle systems in series. The overall IMA is the product of the individual IMAs.
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