Key Terms

Prepared by: learnloophq@gmail.com

Last edited 26 days ago by Learn LoopHQ.

Chapter: 05. Simple Machine

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Machines: devices which make our work easier and faster.

Simple machines: machines that are made up of very few parts and which simply change the direction or the magnitude of force or help us to work faster.

Load (L): the weight to be lifted or moved by a machine.

Effort (E): the external force applied to lift or move the load.

Fulcrum (F): a fixed point about which the machine turns while doing mechanical work.

Load arm: The shortest distance of the load from the fulcrum.

Effort arm: The shortest distance of the effort from the fulcrum.

Velocity ratio (VR): The ratio of the distance moved by the effort to the corresponding distance moved by the load.

Mechanical advantage (MA): the ratio of the load to the effort, indicating how much easier a machine makes work.

Lever: a rigid bar which can move freely about the fulcrum.

Law of levers: states that when a lever is balanced, Load × Load arm = Effort × Effort arm.

Lever of the first order: a lever where the fulcrum is between the load and the effort.

Lever of the second order: a lever where the load is between the fulcrum and the effort.

Lever of the third order: a lever where the effort is between the fulcrum and the load.

Inclined plane: a plane surface that is tilted or inclined to the horizontal.

Screw: a nail with a spiral groove around it, which is a modified inclined plane.

Threads: the windings or spiral grooves around a screw.

Wedge: a piece of wood or metal, that is narrow at one end and broad at the other, formed by two inclined planes.

Wheel and axle: an arrangement in which a wheel is attached to a rod or axle.

Pulley: a simple machine that consists of a wheel with a grooved rim, over which a rope or chain can be passed.

Block: the frame within which the wheel of a pulley is supported and free to rotate around an axle.

Single fixed pulley: a pulley where the block is fixed and the pulley does not move, primarily used to change the direction of effort.

Single movable pulley: a pulley in which the pulley along with its block moves with the load, enabling lifting a load twice the effort.

Block and tackle: an arrangement where several pulleys are used together to lift greater loads with less effort.

Input energy: the energy supplied to a machine, equal to the work done on the machine.

Output energy: the energy produced by a machine, equal to the work done by the machine.

Efficiency: the ratio of the output energy to the input energy.

Ideal machine: a frictionless machine where the work done on it is equal to the work done by it, resulting in 100% efficiency.

Compound machine: a machine made up of two or more simple machines working together to carry out different tasks.

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