4.3 - Mechanical Advantage

Unit 7: Power & Energy
Lesson 3: Mechanical Advantage
& Machine Efficiency

Vocabulary

• efficiency – the measure of how much work put into a machine is changed into a useful output

• mechanical advantage – a measurement used to determine the number of times a machine increases its input force

Making Work Easier

• A machine is anything than has moving parts and can perform a task (can do work)

• Machines make work easier

• A simple machine is a device that accomplishes a ask with one simple motion and without an engine

• Most devices you know are combinations of the six simple machines

Making Work Easier

​If MA = 1, Input = Output
If MA >1, Output > Input (multiples force)
If MA <1, Output < Input (reduces force)

Mechanical Advantage

equals the distance of effort divided by the distance of resistance

​Distance in effort (in m)



Distance of resistance (in m)

Example: Using a block and tackle (pulleys" a boy pulls the rope 10 meters to move the weight up 2 meters. Find the mechanical advantage

• Output Force - what you are LIFTING with the machine

• Input Force- how much you PUT INTO the machine

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Output Force vs. Input Force

Distance of effort - how far you move the object WITH the machine

Distance of resistance - how for the object moves WITHOUT the simple machine

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Distance of Effort vs. Distance of Resistance

Poll

How do you feel about today's lesson?