Lesson video

Hi, everyone.

Welcome to today's lesson.

Today, we're gonna be learning about levers and building that knowledge about levers into mechanical advantage and disadvantage.

Now we're gonna do this simply and we're gonna do it in a way that will hopefully make you understand fully what those levers are.

So by the end of the lesson, you will feel confident that you can draw and label the different components of a lever system.

You will understand the different types of levers and then we'll develop that knowledge and to be able to describe what mechanical advantage and disadvantage are.

Now the keywords for our lesson are very much linked to those components of levers.

Now you may want to pause the recording at this point to just make a note of those, but we will talk about each component in detail.

And then towards the end of the lesson, we will really look at what this mechanical advantage means.

At this point, it's just worth noting that mechanical advantage exists in second class levers.

So our three sections for the lesson are, we're gonna look at those components of a lever.

When we've developed that, we will look at the different types of lever and then we will build that knowledge ready for mechanical advantage and disadvantage.

So let's get started.

And this is a really good starting point.

Let's look at this image and think to ourselves, how would an individual be able to move that rock? Now to me, that rock looks rather heavy and large, but the individual is trying to use a lever or a bar in some way to be able to help him with that movement.

Now did you say that he would probably push down on that and exert a force to be able to move that box? And if you did, well done.

And that might be a really nice start for us to understand the components of a lever.

And actually the magic number is four.

There are four components.

So every lever has an arm.

And if we're talking about our human body, which is where we need to apply these lever systems, that is largely a bone.

So in our image there, we saw that as that being that long bar to help with that movement.

Now if you remember some of your knowledge on bones and joints, bones articulate at a joint and that becomes a fixed point for rotation.

Now in a lever, we referenced this as a fulcrum.

We've already identified that that individual needed to exert some effort to be able to get that box moved.

So in a lever there is always effort and that's often forced, created by our muscles that we know attach to our bones via tendons to be able to move a lever.

And finally, we are often trying to move something.

So we reference that as a load or a resistance that the lever is trying to move.

So in that image, that individual is trying to move that heavy box.

So there are four components.

And when we come to being asked to draw or understand a lever, each of those components is shown as a shape.

So quite simply, the arm or the bone is represented with a straight line.

The fulcrum or the pivot point is represented as a triangle.

The load or the resistance is a square.

And finally, that effort that we know comes from those muscles or that insertion, the tendon of the muscle that attaches to the bone, that is represented by an arrow.

Now that arrow could point upwards because it might be a force that's pushing upwards or it could be a force that's going downwards.

Remember, muscles can pull, not push.

So I should have said pulling upwards or pulling downwards.

Just make a note here of those letters that are a slightly different colour, f, l, e, that's gonna be a really simple way of remembering our lever systems as we move through the lesson.

But quick check at this point, now we know our shapes.

Which of the following shapes represents the fulcrum of a lever? Is it A, a square, B, a triangle, or C, an arrow? Five seconds to decide.

Well done.

It is in fact B.

It's represented us as a triangle.

Now it is worth noting that we need to know that a lever is defined as that bone and it will turn around an axis.

But what is it trying to create? What would be our missing word in this definition? Absolutely, well done if you recognise that when we're referencing the human body, that lever is turning and rotating to be able to create movement.

And that's why we understand it as part of our specification 'cause we've learned about lots of different movements that occur within the human body to allow us to play sport or complete those skills within sport.

So when you do draw them or draw a lever where you position the effort, the load in the fulcrum, will need to be accurate.

So for example, if you look at this diagram here, the straight line is representing the lever arm.

We now know that the triangle is the fulcrum.

And note that that is underneath the line or at the bottom of the line.

The square we now know is the load or the resistance, note that sits on top of the line and so does our effort.

So in terms of drawing them correctly, the triangle goes underneath, the arrow and the square sits on top of the line.

And a quick reminder of our labels, so that triangle is the fulcrum, our square is the load.

And in this instance we've got an upward force for our effort.

So which of the following does a square represent in a lever? Quick check on this one.

Do you think it's the lever, the fulcrum, the load, or the effort? Well done if you identify that our square is the one that sits on the top of the line and is the load.

Now that's a really good link onto our first task to show that we really understand these four components.

So pause the recording and make sure you can complete this table by filling in the missing links, whether it's the component, the icon or the shape that's used, and then the brief description that we have used for those components.

Welcome back.

How did you do? So did you note that the triangle was missing from our fulcrum? We already knew that the next icon or the next shape was a straight line and it was the lever arm.

So did you recognise that that was the component of the lever? Then we have our load as our square and our description of that remember is that it's the resistance or what the lever is trying to move.

And finally, our upward and downward arrows were our effort.

And we know that effort comes from the force created by our muscles that are connected to our bones via tendons.

And I hope you did identify that in terms of those arrows, we have that represented either as an upward or a downward arrow.

So we move on now to our second part of the lesson.

We understand those four components.

Now we need to.

The magic number this time is three and identify or being able to understand those three types of lever.

So there are three classifications.

We refer to them as lever systems. And what Izzy.

Great question from Izzy.

Well, how does she recognise which one is which? How does she know it's either a first, a second or a third lever system? Now the best way of helping Izzy here is talking about the positioning of the shape that actually exists in middle of the lever.

So remember in that first part, we showed a diagram of what a lever system will look like and we positioned them either above or below the line.

We're gonna take that step further now and which ever of shape is in the middle of the other two will determine whether that is a first, a second, or a third class lever.

So to help Izzy with this, I'm gonna introduce you to a rhyme.

And what that rhyme is FLE equals 123.

So what that's telling us is, is in a first class lever system, the fulcrum is in the middle.

In a second, the load is in the middle and in a third, the effort is in the middle.

Now might be a good time to pause the recording and just practise that rhyme, FLE equals 123.

Now use that rhyme to do our first checkpoint.

The load is positioned in the middle of a first class lever system.

Is that true or false? Well done if you picked out that that is in fact false and our rhyme will help us with that, FLE equals 123.

So in fact the load is in the middle of a second class lever and it is the fulcrum that's positioned in the middle of a first class lever.

Now what a really nice link into looking at them each individually.

So we're now just gonna talk about the first class lever system.

Remember our image at the start.

We had our individual pushing downwards on that lever to be able to move that box or that load.

So this is a really good example of a first class lever system because the fulcrum is positioned in the middle.

There you can see our triangle again, it's underneath the line and it's basically at the point of where that bar goes underneath the box.

So on one side of it, you've got the individual who's creating that effort and pushing downwards.

And then the box is the load and that's on the other side of that kind of pivot point.

So we have there a first class lever system because the F is.

The fulcrum, sorry, is positioned in the middle.

So another good example of that could be a seesaw.

Now let's just try and pick that the best we can.

So imagine you're about to go onto a seesaw and you sit on one of the ends.

Now you will become the load at that point 'cause that's what needs moving.

That's the resistance we need moving.

So the seesaw could work in the way that it does.

That pivot point becomes the bit in the middle and we now know that is our fulcrum.

And to move the seesaw or to move you, you would need a partner that would go and sit on the other side and would be applying some effort downwards, which would allow you to move upwards.

So you can see there because the fulcrum is positioned in the middle, this is a really good example of a first class lever system.

Now just to make a point here in terms of the arrow, notice that's pointing downwards.

So in a first class lever system, the arrow tends to point downwards.

A quick way of remembering this is imagine if you've done a race and you're on the podium and there are first, second, and third medals being awarded.

Now if you were in first position, the only way you could change that is by going down to either second or third position.

However, if you're in second or third position, you could better that by going upwards.

So third could go to second, second could go to first.

And I think that's a really interesting way of trying to remind yourself which way you draw the arrow in these lever systems. So for our first class, it's pointing downwards.

Let's look at an example of a second class lever system.

You might wanna pause the recording at this point and have a conversation or think to yourself, "Well, how does that wheelbarrow become a second class lever?" Okay, imagine you put some debris in the wheelbarrow.

That's very common to do that.

Often, that's why it's being used to move heavy loads.

Now that would sit in the middle, so that would be the load.

The wheel of the barrow is at the other side of the load and that becomes our fulcrum or the pivot point.

And it's really common in terms of use of the wheelbarrow that that effort becomes from the handles and that someone needs to lift that upwards to be able to move that and move a lot of those heavy loads.

So a really good example there of a second class because the load is in the middle.

Last but not least.

Let's look at an example of a third class lever system and we're showing how that different shape or component is sitting or position the middle.

So you are now.

Imagine you are now swinging this baseball bat.

Now if you're gonna hit the ball, that gets hit at the end of the bat.

So that becomes the load.

That's what you're trying to move.

If you are holding onto the bat at the end of it, that is the point of where it rotates.

So that's the fulcrum.

Now the effort is very, very close to the fulcrum, but that comes from the muscular force that will travel through your arms to your wrists and be able to rotate that back.

So we can see there really clearly on the image that the effort is sit in the middle of the other two components.

So that makes it a third class lever system.

So just a quick reminder of some examples of each of these class of lever.

First was our seesaw.

Can you remember what our second was? That's right, it was a wheelbarrow.

And then for the third, we gave this example of swinging a baseball bat.

So to help us with remembering that a little check here, which shape was in the middle of the seesaw when it was drawn as a first class lever, is it A, B, or C? Correct, it was the fulcrum because FLE equals 123.

So our F and the one are aligned.

So in the first class lever system, the fulcrum will sit or position in the middle of the diagram.

So we'd shown that layout of the first class lever.

And what I would like you to do now for your second task is use that rhyme, have that going in your head a lot and draw and label a second class lever system.

And once you've done that, remind yourself of that example of the wheelbarrow and explain why that is an example of a second class lever system.

Pause the recording and come back to me when you're ready.

How did you guys do? I'm hoping that as you're drawing and your use of that rhyme that you had the effort load and fulcrum positioned with the load in the middle.

So did yours look like what's on the slide there and did you remember to label it? So the load is in the middle on top of the line, the fulcrum sits underneath and at one end, and at the other end because the load is in the middle, we have the effort, and remember we are thinking about our podium.

And if you're in second place, to better that, you could go up to first.

So our arrow would be pointing upwards.

And the wheelbarrow was a good example of that because someone would do exactly that.

They would lift the handles up so that it then could move the wheelbarrow, which is a nice link into your next question around explaining exactly that.

And you could have said that it is designed to move those heavy loads easily.

That's why a lot of people use it.

The wheel axis the fulcrum or the pivot to be able to move.

The load is in the middle.

That often could be debris or whatever's being tried to be moved.

And the effort is that force comes particularly from the arms but also the legs will help with that to lift the burrow up and then be able to move it.

So finally, now we know our three class of levers and we've developed that confidence how to draw and label them correctly.

We're now gonna move on to be able to describe mechanical advantage and disadvantage.

Now this topic is where it talks about the efficiency.

So how well the lever kind of operates to be able to move those loads.

Now if a lever has high mechanical advantage, it is able to be able to move a large load but with very little effort.

That's how we reference mechanical advantage.

We learn from our keywords really that this exists largely in a second class lever.

Now to understand that more, we need to understand that there are two components to those lever diagrams that we've been looking at.

One of those additional components is an effort arm.

Now what an effort arm is, is the distance between the fulcrum and the effort.

The load arm is the distance from the fulcrum and the load.

When I mean arm, it's probably best just almost recognising that as a line.

So it's showing you the distance between those two components.

So let's just show that as an illustration.

As part of your second task, you had drawn a second class lever.

So a quick reminder of how that looked.

You had the straight line, you'd put the load in the middle, we'd put the effort pointing upwards on one side on top of the line and then the fulcrum was underneath the line at the other side.

Now if we then add our additional two components, the effort arm is basically the distance from the fulcrum to the effort.

Now each of these lines or each of these arms always start at the fulcrum.

So the load arm is the distance from the fulcrum to the load.

Now just looking at that diagram, what do you notice about those two additional components? Hopefully, like me, you can see instantly that the effort arm is longer than the resistance arm.

And this is our second class lever.

Now if I just recap on our three levers that we've already talked about with regards to FLE equals 123, on each of these now, we should be able to add a load arm.

So remember load is distanced from the fulcrum to the load.

So we can see there how that varies quite significantly across the three classes of lever.

The one on the left there is a first.

The one in the middle is a second.

The one on the far right is a third class lever.

The upper arm is gonna be represented as a dotty line.

And if we add that onto there, we can see quite clearly the difference between the two arms in those three classes of lever.

Okay, quick check on this point, at this point, sorry, about our two components.

The effort arm is the distance between the load and the effort.

Is that true or false? Completely agree.

That is false.

The reason why is both of those components remember started at the fulcrum, so the effort arm is in fact the distance between the fulcrum and the effort.

Now think back to what we've just shared and also those in that dashed line, which of the following levers have a high mechanical advantage? So the effort arm would've been longer than the load arm.

Which of these show that mechanical advantage? Well done, it is in fact that second class lever that we had illustrated in our image.

Why? There's our two lines.

The effort arm is longer than the load arm.

So in our second class lever, because of that it is at a mechanical advantage and all that learning we've done on the wheelbarrow kind of makes sense even more sense now because that's why it's designed in the way that it is.

It's about creating a tool or a product where you can move a lot of load but you don't need a massive amount of effort to do so.

So the barrow is designed in that way to support that process.

And Jun completely agrees here.

So there's less effort required to move large loads and he is absolutely correct.

The output is greater than the input.

So that lever system works at a high mechanical advantage.

Good question here.

"In the third class lever, the load arm is longer.

Does this mean there is a disadvantage?" And I like that that question's being asked because yes, the opposite to mechanical advantage is mechanical disadvantage.

And often what that means is the output is less than the input.

So if we've got those third class levers in our human body, the force that is applied needs to be much greater than the load in order for movement to take place.

All right, that is our opposite of mechanical advantage.

So let's do our final practise test to show that we feel confident about those two terms. The first thing I'd like you to do is draw a third class lever system.

So go back to your FLE equals 123 and note that you get the right component positioned in the middle.

Think about your arrow as well and our podium, if they're in third place, would the arrow be upwards or downwards? We're gonna develop that and once you've done that, add the effort and the load arm to that diagram.

And finally, could you link some of our learning in terms of mechanical advantage? So describe why that lever has mechanical disadvantage and what impact would that have on the third class lever? Pause the recording and come back to me when you've finished.

Welcome back.

So first part of the task was drawing the lever correctly.

So hopefully, you got the effort in the middle and the arrow pointed upwards.

You got the fulcrum underneath the line to one side and the load on the other side as a square on top of the line.

We then was developing that further to add the effort arm.

That's quite a small one in this instance.

So you've got that distance between the fulcrum and the effort.

And then you were asked to add a load arm and that was the distance between the fulcrum and the load.

So some correct drawings on that first part of the task.

You were then asked to describe why that lever has mechanical disadvantage.

And quite simply a description there is well, the effort arm, the diagram shows us this, the effort arm is shorter than the load arm.

So what impact does this have? Well, more effort is required to move the load and often there's a smaller range of movement so the input is definitely greater than the output.

And that is very different than our wheelbarrow example that we shared where there is mechanical advantage.

So to summarise our key learning from today's lesson, our body is made up of levers.

Each lever has four components.

We learn about those as the arm or the bone, the fulcrum, which is the pivot point, effort that comes from our muscle insertion, and load, which is the resistance being moved.

We then looked at those three examples or three classes of lever and we spoke at length about our FLE equals 123 and which component is positioned in the middle of those diagrams. I would just ask you as well to look at them and remind yourself of that upward and downward arrow and where those components are positioned in terms of below or above the line.

We then developed that into an understanding about mechanical advantage and knowing that our second class levers are very much the efficient lever 'cause they have the most mechanical advantage.

Whereas our third class lever has the most mechanical disadvantage.

Thank you so much for joining me today and I look forward to seeing you on the next lesson.