Machines

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A machine is a device that helps us overcome a large resistive force (load) by applying a smaller force (effort) at a convenient point and direction, or obtain gain in speed. Main functions: 1) Force

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Mechanical Advantage is the ratio of load (resistance overcome) to the effort applied. Formula: M.A. = Load (L) / Effort (E). It has no unit as it's a ratio of same physical quantities. When M.A. > 1,

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Velocity Ratio is: 1) Ratio of velocity of effort to velocity of load: V.R. = VE/VL, or 2) Ratio of distance moved by effort to distance moved by load: V.R. = dE/dL. It has no unit and remains constan

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Efficiency is the ratio of useful work output to work input. Formula: η = (Work output)/(Work input) × 100% OR η = M.A./V.R. × 100%. For ideal machine η = 100%, for actual machine η < 100% due to fric

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η = M.A./V.R. or M.A. = V.R. × η. For ideal machine: M.A. = V.R. (η = 1). For actual machine: M.A. < V.R. (η < 1) due to friction and machine weight.

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Ideal Machine: No energy loss, output work = input work, efficiency = 100%, M.A. = V.R. Actual Machine: Energy loss due to friction and weight, output work < input work, efficiency < 100%, M.A. < V.R.

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Lever is a rigid straight or bent bar capable of turning about a fixed axis (fulcrum). Principle: Works on principle of moments - Clockwise moment = Anticlockwise moment, i.e., Load × Load arm = Effor

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M.A. = Effort arm / Load arm. When effort arm > load arm, M.A. > 1 (force multiplier). When effort arm = load arm, M.A. = 1. When effort arm < load arm, M.A. < 1 (speed multiplier).