Lesson video

Hi everyone.

Welcome to today's lesson.

I'm Mrs. Brookes.

And today we're gonna be looking at levers, a mechanical advantage.

And that fits within the movement analysis and basic biomechanics section of our specification.

By the end of today's lesson, we will be able to identify each class of lever and also apply that to a sporting example.

Now our key words for the lesson are very much on the three class of lever that we're gonna learn about.

The first class lever, you will learn that there are some components to a lever.

And for a first class lever, the fulcrum is positioned in the middle.

When that comes to a second class, the load is positioned in the middle.

And third, the effort is positioned in the middle.

Now you might want to pause the recording at this stage and take a note of those, but we are going to look at each class of lever in detail.

We'll also talk about mechanical advantage and link that specifically to a second class lever and it works very much as an efficient lever.

So we've got four parts to our lesson.

And we're gonna start by actually looking at the components of a lever.

And then we can start to understand the different types or the three classes of lever, link them to some sporting actions and examples.

And then conclude with understanding what mechanical advantage is.

So as a start, Jacob here is looking at this image and he's asking the question, how will that individual be able to move what looks like a quite heavy rock or box? Now hopefully you looked at that image and thought, well, there's almost like a lever in place that's just gone underneath the rock.

And that individual's probably gonna use some effort and some force and push down on that lever and then that will allow the rock or the box to be lifted.

Now this is a really good way of reminding ourselves what a lever is.

And it has four components and we saw those four components in that image.

One of the components is a lever or an arm.

And if we're linking that to the human body, that's often a bone.

We could see in that image though that was that bar, that quite long piece of metal that that person was trying to use to lift that box.

The fulcrum probably just sat a bit underneath that box.

So it's almost like a fixed point where the the box could rotate or move.

The effort, we referenced the individual being able to use that muscular force to push down on that lever.

And in our human body, that force is created by our muscles and often that is done by being attached to bones by tendons.

And then when they do contract, they create that movement.

And finally, our levers are trying to move a load or move a resistance.

And we saw that with the box and the rock within that image.

So there are four components, our magic number of four.

Now, to make that even more simple, each of those components is shown as a shape.

So for our lever or our arm that is referenced as a straight line, A fulcrum or the pivot point that is referenced as a triangle.

When we talk about load or resistance, that is drawn as a square.

And finally the effort that we now know comes from a muscle or a muscle insertion, that will be an arrow.

Now that arrow could be either pointing upwards or it could be pointing downwards.

So when you have to reference or you have to draw a lever, essentially all you are drawing is four separate shapes.

Now just be aware there, you can see the F, the L and the E on a slightly different colour, and that's on purpose.

So we're gonna talk about those three letters as we move through the lesson.

But before we do that, let's just have a quick check on our shapes.

We have three of those shapes here, but which one of those represents the fulcrum of a lever? I'll give you five seconds to decide.

Well done.

That is in fact represented as a triangle shape.

Now what happens with these components is they get drawn in a certain way and they have to be positioned correctly above the line.

So we always draw the line as a starting point and we now know that is the lever arm or the bone.

The triangle or the fulcrum will always go underneath the line.

Whereas the square will go on top of it.

And our arrow remember can be upwards or downwards.

But in this diagram we can see it's actually pointed upwards, also sits on top of that line.

And it's very common that we'll see them labelled correctly as well.

So a quick reminder there, the triangle is our fulcrum, the square is representing the load or the resistance, and the effort is that force created by our muscles.

So we've got our shape here of the square.

Which of those four components does that actually represent in the lever? Is it the lever itself? Is it the fulcrum? Is it the load? Or is it the effort? Really well done.

Our square represents the load within a lever system.

So that's a nice link into our first task.

Simply here we have a table, it's divided into three columns, whether it's the component of the lever, the shape or the icon that's used, and then a small description about each of those components.

You can see there are some bits already complete, but could you now pause the recording and fill in those missing spaces? Well done.

How did you do? So for the fulcrum, did you remind yourself that that is actually shaped as a triangle? For the straight line, we know that's the lever arm or the bone.

For the load, did you add that square and then that description that it is the resistance, it's what the lever is trying to move? And finally, the effort as an upward and downwards arrow and we know that is the force, the muscular force created to be able to move that lever.

So now we know our components of a lever system.

We need to understand how those components work and sit together in our three types of lever.

So yes, that's right.

There are three classifications of lever that we need to know about that exist in the human body.

We often refer to them as lever systems. So Izzy is asking a really good question here.

How do I recognise each lever system? Well the first thing to know is that they will be called as a class.

So we have a first class lever, a second class, and a third class lever.

Now the way to recognise them is all linked to the component that sits in the middle of a lever diagram.

So I've already shared with you what a diagram looks like and how we position those components above or below the line.

So now we're gonna take it that step further and consider which of those components actually goes in the middle.

And when we know that, that will determine whether it's a first, a second, or a third class lever.

So what I'm going to share with you now is a really simple but memorable rhyme which will help us understand these three types of lever.

And how that rhyme goes is very simply FLE equals one, two, three.

So in a first class lever system, the fulcrum is actually positioned in the middle.

So the F and the one are aligned.

Likewise for the L and the two.

So the load is positioned in the middle.

And for a third, yes you've guessed it, the effort is positioned in the middle.

So you might wanna pause at this point and actually just practise saying FLE equals one, two, three.

Now a quick check with that rhyme.

Question here is asking us about the load and if it is positioned in the middle of a first class lever system, do we think that's true or false? Well done.

That is in fact false.

And if we've used our rhyme of FLE equals one, two, three, the fulcrum, the F is linked with one.

So that is actually positioned in the middle of a first class lever.

Whereas in the second class lever, that would've been the load.

So let's look at each class of lever now and we can start with our first class lever and we'll revisit our image that we did right at the start of the lesson.

Remember we had that individual that was exerting that force on that lever to be able to move that load.

Now if we draw that as a first class lever system, this is exactly how it will look.

So the fulcrum of the triangle is that kind of pivot point.

That bit there you can just see that exists underneath that box or that rock.

The effort we know is coming from the individual and he's doing that downwards force to create some effort.

So we can see there the effort is pointing downwards.

And obviously the load is the box or the rock that's trying to move.

And we can see here that the fulcrum is positioned in the middle.

A quick description here for the effort, of whether it needs to be upwards or downwards.

Imagine if you are in first place at the end of a race, that would mean you would go on a podium and you would be stood in that first position.

Now the only way you can change that is by go dropping into either second or third.

So that's a really good way that the downwards arrow for a, sorry, the arrow for a first class lever is going to point downwards.

Now another good example of this is the seesaw.

So let's imagine we're heading to the playground and we come across a seesaw.

And I imagine if we want to kind of use it, we would sit on one side of it and what that would mean is there we would become the load.

So we can see there that we're representing that correctly as a square.

The middle of the seesaw is almost that pivot point, that fulcrum.

And if we want to then be moved, we need someone to come and sit on the other side, a partner, and move the seesaw by applying that effort downwards.

So not only can we see the image there of the seesaw, we can see how those components have been positioned and the fulcrum is positioned in the middle.

Now an example of a second class lever is the wheelbarrow.

Now just look at that image and could you kind of maybe work out how and why that is a second class lever.

Now the first thing to consider is, imagine like the wheelbarrow is used that you would fill that up with lots of debris or things that need moving and often those things are lots of them or they're rather heavy.

So that would be the load and we would place that in the middle or where that debris would sit.

The actual wheel of the barrow is a pivot point or a fulcrum.

So when that actually goes onto the wheel, that becomes that point of movement.

And that force comes from someone who then actually lifts up those handles to be able to then pop it onto its wheel so that that debris can be moved.

So we can see a real difference here compared to the seesaw and we've actually got the debris or the load that's sitting in the middle or positioned in the middle.

So for our third class lever, we're going to look at a baseball bat or a baseball swing.

So imagine you are now that athlete who's about to swing and hit that baseball.

Now you hitting the ball or you move in that heavy bit of the bat, that is the load.

Now the other end of the bat, the bit where you are holding onto it, that becomes the point of rotation or the fulcrum point.

And the effort is really close to that.

But actually it comes from the arm muscles that will then move the wrists and the elbows to be able to swing that bat and then hit that ball.

So we can see there clearly from the the diagram that those three components have been added and the effort is positioned in the middle.

So quick recap of our three examples there.

We had the seesaw as our first class example.

Wheelbarrow as a second.

And third class, yes, you've remembered, it was that baseball bat.

So if we look at our seesaw in particular, which of the components or which of our shapes is correct for the seesaw and drawn in the middle of our first class lever system? Is it A, B or C? Completely agree that was our fulcrum point.

And therefore the triangle was the correct answer.

Now because we've looked already at a diagram of our first class lever system and it's just there to remind ourselves what that looked like, I would like you to use your rhyme FLE equals one, two, three, and then draw and label a second class lever system.

Once you've done that, link it to our example of a wheelbarrow but give an explanation as to why that is an example of a second class lever.

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

How did you get on? Did that rhyme help? And did you make sure that you positioned the load in the middle of your diagram? We can see there, we've got the load and it's sitting on top of the line.

The fulcrum a little bit like the wheelbarrow or the wheel is on the end and sits underneath the line.

And then the effort is on the opposite side.

And we use an upwards arrow this time.

And think back to our podium, if you are in second place, if you wanted to better that, you would move up into first.

So we've got that upwards arrow in our second class lever.

We were then asked to make an explanation as to why the wheelbarrow is an example of a second class lever system.

So we need to develop some points.

Now those points could have been round the fact that the wheelbarrow is very much about moving heavy loads with ease.

And then just developing that more by saying that the wheel is the pivot point or the fulcrum, the load would be placed in the middle, and then the effort would be that force that would come from someone lifting the handles to be able to move the burrow or move that large load.

So now we have our three examples of our first, second, and third class lever.

We need to link this to sporting examples or actions within the sport.

So let's just note the middle component of our diagram 'cause that aligns with our FLE equals one, two, three.

So our first class, the fulcrum is positioned in the middle.

Our second class, the load is positioned in the middle.

And finally our third class is positioned with the effort in the middle.

And we can see that upward arrow again in the third class.

A little bit like our podium, if that third place wants to better that position, they could move upwards into either second or third.

Now think about your learning around joint movements.

We know bones articulate at a joint.

So for our first class lever, the movement at the neck as I'm doing now is a first class lever movement.

So can we demonstrate our head in a ball what that would look like? So imagine few of you have leant back and then move your neck forward to show how you would connect with a ball and the ball hit you on the forehead so you could then direct it to where it needs to go or to move it away if you were doing it as a defender.

So this is a good way of kind of showing that movement what we've just done.

And notice I've added the components to the diagram.

So the fulcrum is sitting very much in the middle because that's the joint.

And that's where our top of our vertebrae connects with our cranium.

We know the load is often the ball or what that lever is trying to move.

And then the effort is working downwards and it's those muscles that sit in the back of the neck that are creating that neck movement.

Now if we then going to look at a second class lever example, we're actually gonna talk about pointing the toes and actually making a movement at the ankle.

So could you now demonstrate like I've just done what pointing the toes at the ankle actually looks like.

And I suspect either underneath your desk or if you're standing, you've done exactly that and you've gone upwards onto your toes.

A little bit like this.

So that pivot point is now the toes as you are on there.

The load in this instance is gravity 'cause it was that gravity who's trying to pull you back down and you are having to work against that to move upwards.

And that will always kind of take effect from the middle of the body.

And the effort is that muscle, that muscle group at the back of the lower leg and back of the calf that we know is the gastrocnemius.

So moving on, we're now looking at an example of a third class lever.

And we, in this instance, it's actually flexion of the elbow.

So maybe you can demonstrate that in the same way I've done.

You could do it with one arm or you could do it with both arms. And in both cases, you would just be showing you'd be bringing that wrist up towards the head.

Now if we see this anatomically, we can see there we've got the bones, the humerus, the radius and the ulnar, and they are connecting at the elbow joint.

So that becomes our fulcrum.

If we were to have a weight in our hand, that would represent the load.

And what's really interesting about this, look at the bicep muscle, that muscle at the front of the upper arm and look how it's connected to that radius bone.

And that's the bone that when that muscle pulls, it pulls that bone upwards.

So in terms of the effort, that starts at that point for our bicep muscle.

And we can see clearly there that the components are positioned in the way that the effort is in the middle.

So we've got our example of our third class lever system.

So look at our GCSE student here.

And we've got an extension of the rhyme, FLE equals one, two, three equals NAE neck, ankle, elbow.

Like our student, can you practise and say the rhyme at the same time? Notice that on one, he's doing the N.

That's his first movement.

On two, he's going up onto his toes.

That's the ankle.

And on three, he's going to flex the elbow, that third movement.

Now as you're doing and saying that, what does that remind you of? Exactly, those movements that we've already referenced.

So for the neck, we've got heading the ball, pointing the toes at the ankle, and then flexion of the elbow.

Really simple movement patterns that allow you to recall this key information about our three classes of lever.

So now we've got those three areas of the body.

Quick check here, which part of the body is an example of a first class lever system? Think about those actions that that student was doing.

Is it the ankle, the elbow, or the neck? Well done, it is in fact the neck.

And how we remember that is really simply with our rhyme, FLE equals one, two, three, NAE, neck, ankle, elbow.

Which should allow us with this checkpoint to correctly identify examples of a second class lever.

Note on the images, the joint has been circled or identified for us.

Five seconds to decide which images you would choose.

Well done if you went with image A and C.

We can see that sprint start there and that ankle pushing off the floor or the blocks.

Likewise, that skater movement where you would move off one foot, go up onto the toes before going onto that alternative foot.

Both of those are operating at the ankle.

So according to our rhyme and actions are a second class lever.

However, image B is showing a bicep curl, which is shown flexion of the elbow, which was that third movement that our GCSE student completed.

Okay, let's look at these images then.

On which of the following of these is the correct joint movement for a third class lever? Is it image A, B, or C? Really well done.

That actually is B.

Because we can see that flexion, that arrow is showing that the arm is gonna move upwards towards the head.

Whereas A is the ankle, which we now know is our second class.

And even though in image C, we have got flexion of the elbow.

What that's going to then do is actually going to an extension movement.

And that is not showing that flexion like we saw with our GCSE student.

Which moves us nicely onto our third task of the lesson.

We've got three sporting actions here.

We have a set shot in basketball.

We have the run-up, the takeoff, the jump, and the landing for high jump.

And we have someone that's doing a bicep curl movement.

Notice the arrows are pointed to the joint that we need you to reference as part of this task.

So for our basketballer at the neck.

For our high jump at the ankle as they're about to take off.

And then at the elbow for our bicep curl movement.

What I'd like you to do is first of all identify the correct lever system.

And then once you've done that, draw an accurate diagram for each of those lever systems. Pause the recording and come back to me when you're ready.

Well done.

These were in a nice order for us in terms of that neck, ankle, elbow, NAE.

And we can see for our wheelchair basketball athlete, we've got a first class lever working at the neck.

At the ankle, our second for our high jump athlete.

And for the bicep curl, third class.

And underneath is our reminder of our diagrams and how they should be set.

Just note the position of the component in the middle, which is a nice link to our diagram, our rhyme, sorry, FLE equals one, two, three.

And it's also got our component of the fulcrum underneath the line, the effort and the load on top, and we also see that arrow pointing correctly.

For our first, pointing downwards.

Remember if you're on the top of the podium, you would only be able to go down.

But for second and third, you can better that position by going upwards or going up into that first position so that upwards arrow.

So well done on understanding those components, knowing our three classifications, and now knowing the neck, the ankle, and the elbow are really good examples of sporting actions of those three levers.

So to conclude and to finish with, we are gonna look at this term mechanical advantage, and be able to give a description of what mechanical advantage is.

What I can tell you is mechanical advantage is when you're referencing the efficiency of the lever.

Now in order to understand it better, we are going to add two components to our lever diagrams. Those components are, or one of those components is the effort arm.

Now we mustn't get confused here in terms of the effort with the upward and downwards arrow, that still exists.

This is like an additional line or an additional arrow which shows the distance on a diagram between the fulcrum and the effort.

There will also be some distance between the fulcrum and the load.

So what we refer to as that in this instance is the resistance arm.

So we have got two additional lines or components of sections that we can add to a diagram.

But in doing so, it helps us understand this term mechanical advantage.

So to show you that in practise, I'm gonna show an illustration here of a second class lever.

We would always start with the line.

We know that it's a second and the L is in the middle according to our rhyme.

So the load would be positioned correctly in the middle and on top of the line.

And then at either side, we would have the effort pointing upwards and then the fulcrum at the other side underneath the line.

Notice now what I've done here with this black line or arrow.

I've showed the distance between the fulcrum and the effort.

So we call this the effort arm.

And I've added this second component and that's showing the distance between the fulcrum and the load, and that's known as the resistance arm.

Now what do you notice about the effort and the resistance arm, now we've added those components? Exactly, I completely agree, that's the first thing I notice.

That effort arm is longer than the resistance arm.

Now let's just make sure we understand about that two new components.

Is the effort arm the distance between the load and the effort? Do you think that's true or false? Absolutely, this is false.

And the reason it is false is that both those new components start from the fulcrum.

So in this instance, the effort arm is between the fulcrum and the effort, not the load and the effort.

Now when we calculate mechanical advantage, we use those two components.

So we actually divide the effort arm by the resistance arm.

So that can give us a figure.

And we look at that in terms of if a lever is working at advantage or a disadvantage.

So in that second class lever, we absolutely did see that that effort arm was longer than the resistance arm.

So that means that a second class lever is operating at high mechanical advantage.

It's really efficient.

And because it's efficient, that means it can move large loads with relatively low effort.

And we spoke about the wheelbarrow, didn't we, as a really good example of a second class lever.

And now this adds to our explanation that that's why it's designed in that way.

Because it's efficient as a lever, the load goes in the middle, which means those large loads they do need some effort to be moved, but it's less effort because of how it's positioned with those components.

So of our three diagrams, which we're super familiar with now, which of them show a high mechanical advantage? Absolutely B is our second class, so that's the one we'd looked at together.

You may have hopefully also identified that a first class lever, which is image A, could also have a high mechanical advantage.

It will depend on the position of the fulcrum, but there are times where if that fulcrum is positioned a little bit more towards the load then there will be an example of high mechanical advantage.

Now the one we didn't tick, our third class lever is a nice link into our final task.

We've drawn a first and a second class lever, so for your final task, I'd like you to draw a third class lever and consider the one that we would talk about in terms of flexion of the elbow.

Once you've done that, add our two additional components, add an effort arm and a resistance arm.

And from that, describe why that lever has a low mechanical advantage.

And if we linked it to our sporting action of the bicep curl, what impact does that low mechanical advantage have? Four parts to this task.

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

Well done.

So for our third class lever, yours should look something similar to this on the slide.

Our effort is definitely in the middle given our rhyme.

Probably quite close to the fulcrum if you were referencing this flexion of the elbow.

And our load at the other end sitting also on top of the line.

Now we were developing this more so to include the effort arm.

So that should have been shown for that starting at the fulcrum and going towards the effort component.

And then also looking to add the resistance arm also starts at the fulcrum, but then is that distance to the load.

And in terms of description for low mechanical advantage, what that drawing showed you is that effort arm is now shorter than the resistance arm.

And that's different to what we looked at in that second class lever where it was longer.

So that means that we're at low mechanical advantage.

So what impact does that have on our bicep curl? Well what you could have said is, more effort is needed particularly from that biceps muscle to generate the force required to be able to move that weight.

And that makes sense as well that if people are wanting to lift heavier weights, what they do is they have to strengthen that muscle.

'Cause it's operating at that low mechanical advantage, more force and effort is required.

So in summary, we've learned lots today about this topic of levers.

But we know now that are three classes of lever.

And for our first class, we saw our student doing neck flexion and extension as an example.

And we linked that to a sporting example such as heading a football.

For a second class lever, you had that pointing or going onto the toes at the ankle.

Lots of different sporting actions where that happens.

We looked at a really simple example of where you push off the floor in a sprint start.

And that third class lever our neck, ankle, elbow, we looked at that flexion of the elbow.

And simply used a really common example of that, which is where you've got that bicep curl movement where you will bring a weight up towards the head.

And from that, we learned about mechanical advantage.

And we know now that it occurs the most in a second class lever.

And that's a good thing, that's an efficient thing, because less effort is required in order to move those larger loads.

Thank you so much for joining me today on this topic of levers.

And I look forward to seeing you on the next lesson.