Understanding Machines and How They Work
Machines are tools that allow us to do work in a way that is easier than using our own physical strength. Although some machines can be quite simple, they all work by changing at least one of
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About Understanding Machines and How They Work
PowerPoint presentation about 'Understanding Machines and How They Work'. This presentation describes the topic on Machines are tools that allow us to do work in a way that is easier than using our own physical strength. Although some machines can be quite simple, they all work by changing at least one of. The key topics included in this slideshow are . Download this presentation absolutely free.
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Slide1How domachines work?
Slide2What is a machine?• Allows you to do work in a way that is easier • Can be quite simple • A machine changes at least one of three factors…
Slide3The 3 Factors of Work1. Amount of force you exert 2. The distance over which you exert your force 3. The direction in which you exert your force
Slide4Input and Output Forces • Remember… when you use a machine to do work, you exert a force over some distance. • The force you exert on the machine is the input force. • The force the machine exerts on an object is called the output force.
Slide5The output work done bythe shovel can never be greater than the input work done by the gardener.
Slide6Input and Output Work • Input force times input distance is called the input work. – Done by the person – Think “I” do i nput work • Output force times output distance is called the output work – Done by the machine
Slide7•The output work done by the shovel can never be greater than the input work done by the gardener. • Input work and output work can vary depending on the distance the force exerted. • Small input force exerted over a long distance = large output force exerted over a short distance
Slide8Making Work EasierBy Changing Force, Distance or Direction
Slide9Changing Force
Slide10Changing Distance
Slide11Changing Direction
Slide12Mechanical Advantage• Mechanical advantage is the number of times a machine increases a force exerted on it. – Think: “How was the force changed?” MA OF IF No units! : )
Slide13Mechanical Advantage• If MA is over 1: – Force is multiplied! (output force more than input, output distance is less) • If MA is less than 1 – Distance is multiplied! (output force less than input, so output distance is more) • If MA = 1 – Machine only changes direction – force and distance are the same for input and output
Slide14Efficiency of Machines• Assuming the input work is exactly equal to the output work is ideal , this is not always the case • The efficiency of a machine compares the output work to the input work. • Efficiency is expressed as a percent. • The higher the percent, the more efficient the machine is.
Slide15Efficiency of MachinesWhat may be the cause of having a less efficient machine? Consider the difference between a new pair of garden shears and an old rusty pair of shears.
Slide16Efficiency of MachinesTo calculate the efficiency of a machine, divide the output work by the input work and multiply the result by 100 percent.
Slide17Calculating Efficiency
Slide18Calculating Efficiency
Slide19Real vs. Ideal Machines• An ideal machine is 100% efficient. – Does not exist! • A real machine is less than 100% efficient.