Simple Machines Bozeman Science English (auto-generated) English

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hi it's mr. Andersen and today I'm going to talk about simple machines before we

Hi. It's Mr. Andersen and today I'm going to talk about simple machines. Before

talk about simple machines however we should define what a machine is a

we talk about simple machines however we should define what a machine is. A machine is any

machine is any device that uses energy to do work one of my favorite machines

device that uses energy to do work. One of my favorite machines is the bicycle. It allows

is the bicycle allows me to move around town very quickly when there's not too much snow on the ground now that we've

me to move around town very quickly when there's not too much snow on the ground. Now that

defined a machine as anything that can use energy to do work we should probably

we've defined a machine as anything that can use energy to do work, we should probably

define what work is work is in science defined as a force exerted over a

define what work is. Work is, in science, defined as a force exerted over a distance.

distance and let's say so let's say I lift an apple an apple has a weight of 1 Newton and I lift it one meter well then

And so let's say I lift and an apple. An apple has a weight of 1 newton and I lift it 1 meter.

the work is the force times the distance or 1 Newton times 1 meter or one Joule

Well then the work is the force times the distance or 1 newton times 1 meter or 1 joule

of work is done and I could use a simple machine to do such a task on so if we

of work is done. And I could use a simple machine to do such a task. So if we look at

look at the bicycle again that machine and we tear it down to into its

the bicycle again, that machine, and we tear it down into its individual parts, what we'll

individual parts what we'll find is that this complex machine is actually made up of much simpler parts and if we pair

find is that this complex machine is actually made up much simpler parts. And if we pair

that down to the simplest of simple parts we call those simple machines and

that down to the simplest of simple parts, we call those simple machines. And there's

there's some debate on what actually makes up a simple machine the the general list of six simple machines kind

some debate on what actually makes up a simple machine. The general list of six simple machines

of grew right out of the Renaissance and the work of da Vinci on some of his

kind of grew right of the Renaissance and the work of da Vinci on some of his earliest

earliest drawings of machines and so in general that are defined as the lever the wheel and axle the pulley the

drawings of machines. And so in general they're defined as the lever, the wheel and axel,

inclined plane the wedge and the screw and a definition for what a simple

the pulley, the inclined plane, the wedge and the screw. And a definition for what a

machine is is any mechanical device that changes the direction or the magnitude

simple machine is is any mechanical device that changes the direction or the magnitude

of a force now you'll find that some of the things were left off that list that

of a force. Now you'll find that some of the things were left off that list that you might

you might think of as simple machines a gear is simply a detailed example of a wheel and axle and hydraulics is

think of as simple machines. A gear is simple a detailed example of a wheel and axel. And

interesting hydraulics allows us to magnify our forces and so we maybe

hydraulics is interesting. Hydraulics allows us to magnify our forces. And so we maybe

should include that in our list of simple machines now the more in detail

should include that in our list of simple machines. Now the more in detail you look

you look at simple machines what you'll find is that all simple machines are

at simple machines, what you'll find is that all simple machines are actually one of two

actually one of two different types they are either a lever and a wheel and axle

different types. They are either a lever and a wheel and axel and a pulley are examples

and pulley are examples of a lever they are an inclined plane and a wedge is simply to incline planes and a screw

of a lever. Or they are an inclined plane. And a wedge is simply two inclined planes.

as an inclined plane wrapped about a cylinder and so the easiest way to look

And a screw is an inclined plane wrapped about a cylinder. And so the easiest way to look

at simple machines is to look at these two types and so first let's talk about the lever you've learned about levers

at simple machines is to look at these two types. And so first let's talk about the lever.

probably your whole life the parts of a

You've learned about levers probably your whole life. The parts of a lever are going

lever are going to be the arm and then the fulcrum and so there's an old quote that says if I had a lever long enough

to be the arm and then the fulcrum. And so there's an old quote that says if I had a

and a place to rest it I could lift the

lever long enough and a place to rest it I could lift the world. And so let's look at

world and so let's look at that lever on one side you have the world or the earth and on the other side you have you the

that lever. On one side you have the world or the earth. And on the other side you have

fulcrum then sits right in the middle and so you input a force on one side of

you. The fulcrum then sits right in the middle. And so you input a force on one side of the

the lever we call that the input force or F sub I and you get an output force

lever. We call that the input force or F sub i. And you get an output force on the other

on the other side and that's called F sub o or output force and so we can look

side. And that's called F sub o. Or output force. And so we can look at any kind of a

at any kind of a lever and we can measure how well it does at magnifying your input force and we call that

lever and we can measure how well it does at magnifying your input force. And we call

mechanical advantage so mechanical advantage is defined as the ratio

that mechanical advantage. So mechanical advantage is defined as the ratio between the output

between the output force and the input force and so when you push down on one

force and the input force. And so when you push down on one side of a lever, for example

side of a lever for example with a input force of 2 and you're able to magnify that and get an output force of 10 that

with an input force of 2 and you're able to magnify that and get an output force of 10,

would be a mechanical advantage of 10 divided by 2 or 5 now you probably know

that would be a mechanical advantage of 10 divided by 2 or 5. Now you probably know that

that in science you don't get anything for free and so what's the magic of a

in science you don't get anything for free. And so what's the magic of a simple machine?

simple machine well there's not really any magic at all remember we defined work as force times the distance and so

Well there's not really any magic at all. Remember we defined work as force times a

if you look at a lever you may be implying a less force let's say a 2

distance. And so if you look at a lever, you may be applying a less force, let's say a

Newton force but you have to apply that over a greater distance and so on the

2 newton force. But you have to apply that over a great distance. And so on the other

other side on the output side you may get a greater force but you're going to

side, on the the output side, you may get a greater force but you're going to only get

only get that over a less distance and so our mechanical advantage can be greater than 1 if we're ever magnifying

that over a less distance. And so our mechanical advantage can be greater than 1 if we're ever

our force or it can be less than 1 if we're trying to increase our distance so

magnifying our force. Or it can be less that 1 if we're trying to increase our distance.

your arm for example has a mechanical advantage much less than 1 what does

So your arm for example has a mechanical advantage much less than one. What does that allow you

that allow you to do it allows you to have a greater length of mobility the

to do? It allows you to have a greater length of mobility. The other type of simple machine

other type of simple machine is the inclined plane and so inclined plane allows us to talk about a term called

is the inclined plane. And so the inclined plane allows us to talk about a term called

efficiency so let's say that we're lifting a to Newton force or a to Newton weight

efficiency. So let's say that we're lifting a 2 newton force, or a 2 newton weight. And

and we want to list that one meter but it's too heavy for us to lift and so

we want to lift that 1 meter. But it's too heavy for us to lift. And so instead of doing

instead of doing that we use an inclined plane let's say using an inclined plane instead of applying a two Newton force

that we use a inclined plane. Let's say using a inclined plane, instead of applying a 2

we're able to apply a force of 0.2 Newtons the problem with an inclined

newton force we're able to apply a force of 0.2 newtons. The problem with an inclined

plane is that we have to actually drag it a greater distance let's say we have

plane is that we have to actually drag it a great distance. Let's say we have to drag

to drag that 12 meters instead of one meter well we don't have to pull as hard

that 12 meters instead of 1 meter. Well we don't have to pull as hard, and that's the

and that's the reason that going upstairs is easier than climbing up a ladder but we're actually putting more

reason that going up stairs is easier than climbing up a ladder. But we're actually putting

work in and we're losing that some of that energy to the friction of the

more work in. And we're losing some of that energy to the friction of the inclined plane

inclined plane itself and so there's when you say that a simple machine allows you to do more work it's probably

itself. And so there's, when you say that a simple machine allows you to do more work,

not true what you're doing is you're actually doing more work by doing this

it's probably not true. What you're doing is you're actually doing more work by adding

adding a simple machine but you're able to change the direction or the magnitude of the force and so we use a term called

a simple machine. But you're able to change the direction or the magnitude of the force.

efficiency efficiency is when the input work and the output work are identical

And so we use a term called efficiency. Efficiency is when the input work and the output work

and 100% efficient simple machine simply does not exist we usually have to put

are identical. And 100 percent efficient simple machine simply does not exist. We usually

way more work into a machine than we're able to get out of it and so that simple

have to put way more work into a machine than we're able to get out of it. And so that's

machines and I hope that's helpful

simple machines. And I hope that's helpful.