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Engineering, math.

All coming up right now on Alabama STEM Explorers.

Hi, and welcome back to Alabama STEM explorers.

I'm Anderson, and this is my new friend Wendy, and we're here at Barber Motorsports in Birmingham, Alabama.

Welcome.

Have you ever been to Barber Motors Motorsports Museum?

I don't think so.

I mean, it's really cool to see all these bicycles and stuff.

I really like it.

Well, you are standing in the world's largest motorcycle museum.

We have almost 1900 motorcycles in our collection.

And are all this, like, on display for everyone to see?

Not all of them.

ll see about a 900 to 1000 of them on display.

Any time you come visit the museum.

That's amazing.

I know.

So, have you ever ridden a motorcycle before?

Well, my little brother actually had a kind of a smaller motorcycle thing, and so I would ride it around the soccer field sometimes.

And it was really fun.

I don't think it was like a real full size motorcycle.

I thought I was about to think, you're going to tell me a story we shouldn't talk about.

Well, today we're going to talk about how a motorcycle can lean without falling over.

So riding a motorcycle is a lot like riding a bicycle.

A lot of the same physics go into it.

I've seen like people driving their motorcycles on the TV and everything where they'll be like, I'm on their side.

And I always thought that was crazy.

That could just like kind of stay off.

Yes.

So I have a question for you.

At what degree of an angle do you think it's possible for a motorcycle to lean if you had to guess?

So would it be like kind of more this way?

What degree, how many degrees do you think?

I'm not go with degrees, maybe.

Would you believe that a motorcycle can lean up to 64 degrees?

They can lean so far that there's the motorcyclist side of their body can actually skim the ground.

What?

Yes, it's very extreme.

And when they are leaning that far, like how are they like are they controlling that with the steering wheel?

That's a really good question.

So we're going to talk about the basic physics that go into how a motorcycle can lean without falling over.

But before we start, I'm going to introduce just a few vocabulary words to help us along the way.

Okay.

So first we have force, which is any pressure pole that causes a change in motion.

Okay, next, we have gravity, a force that pulls everything toward the earth.

Oh, those are probably familiar to you.

Okay.

Have you taken physics classes yet?

Oh, I'm actually in physics right now.

Excellent.

So some of this might be familiar to you.

We have acceleration, which is a velocity changing over time, and it's in terms of speed and direction.

So just going fast moving forward, we think of it as going forward.

Yes.

And acceleration actually has a lot to do with gravity and with torque.

And we'll we'll talk about that in just a minute.

And then we have angular velocity, the rate of rotation around an axis.

And last, we're going to talk about centrifugal force, which literally means center fling.

So a force that takes you away from the center of something of the axis of something.

So the center of the motorcycle is the wheel?

Would that be the wheel?

Would that be the center of the motorcycle?

You're very close.

Yes.

And actually, to have equilibrium on a motorcycle it's standing up, it's down the center of the writer's body and down the center of the motorcycle.

So that's why when you're on a motorcycle, you have to be really careful so you can stay up.

That's absolutely right.

And we're going to talk about that in a little bit, too.

So you're already catching on.

So we're going to break this down a little bit.

And I'm going to have you do a couple simple experiments just to isolate some of these forces.

Okay.

So the first one is this.

I'm going to have you pick up these two beanbags and just hold your arms out straight and then just drop them on the table.

Okay.

So what force was acting on those beanbags?

Gravity.

Absolutely.

Yep.

Gravity is what pulls everything toward the center of the earth.

And it is also what pulls a motorcycle down toward.

Toward the earth.

Right.

That helps with the equilibrium.

Okay.

So we talked about gravity.

We're going to add another force to help us understand and get a little closer to how motorcycle can turn or lean in their turn without falling over.

Okay.

So we are going to I'm actually going to have you sit in this chair, hook chair here.

Yeah.

So we're going to scoop the chair out here.

I love you.

Scoot all the way back and hold on to the handles.

So we were standing still when we dropped the beanbags.

So I am going to push you very quickly across the floor.

Are you ready?

I'm ready.

Okay.

All right.

Let's move you back to the center.

Now go ahead and stay seated.

Tell me what happened to your body when we accelerated forward.

I went back in my chair more.

That's right.

You felt like you were being pushed back.

Right.

So that's an opposite reaction to accelerating forward.

Okay.

That's going to be important later when we bring all of this together.

Okay.

So what about if we add a spin to the chair?

Are you ready?

I'm ready.

Okay.

So I'm going to bring you back over here.

I'm going to spin you.

All right.

So what happened to your body when I spin the chair?

I was still kind of getting pushed back, but I was also getting flung kind of to the side, too.

Absolutely right.

So now we've we have gravity acceleration and a new force called centrifugal force acting on your body.

So when you're in a car and it turns a corner really fast, you automatically want to lean the opposite direction.

Right.

So just to bring that point home, if if we didn't have some force holding us in place.

Okay, we're going to find out what would happen.

So if you could put your feet up on here, I'm going to this is a makeshift cell phone.

I'm going to set this on your lap right here.

I can get it to stay.

Can you kind of get up on your Oh, yeah.

Okay, so now think about what happens if you set your cell phone on the car seat on the seat of the car, on your leg, and you're not holding on to it.

And you go around a corner really fast.

What's going to happen to your cell phone is probably going to fall.

Let's see what happens.

I'm going to give you this.

I'm ready.

I'm going to spend you in the same direction.

We're going to see what happens to our cell phone.

Okay.

Okay.

Oh, sorry.

That's okay.

You all right?

Oh, yeah, I'm perfectly fine.

So what happened?

Exactly what we thought was going to happen.

The cell phone doesn't have anything holding it in place, so it wanted to fling out to the side of that centrifugal force.

It's a force that makes something want to go out from center.

So if there was a block and I was trying to or a tree and trying to move after we cut it down and you're moving it this way, is that centrifugal force or is that just putting force on it?

That's a really good question.

Are you rolling the tree or are we just pushing the tree?

If we're rolling it?

Like, how would that.

Okay.

Well, we would be putting a force on the tree, but that is not exactly the same force that we're using when we're riding our bike, our remote, our our motorcycle.

Oh, okay.

All right, so let's go ahead and stand up.

We're done with this chair.

We're going to come back around here.

All right.

We're going to move these things.

So now we've talked about we've talked about gravity, we've talked about acceleration, and we've added centrifugal force.

So we have all of these forces working together.

Well, those aren't all of them.

Oh, I know.

So we're going to do another little experiment, and this is going to isolate another couple of forces, which are torque and angular velocity.

Okay.

So remember, angular velocity is the rate of rotation around an axis.

So an axis is in the middle.

All right.

So we're going to use this pencil.

Very simple experiment, but I think it'll help you understand.

So I'd like you to take two fingers and place them on either side of the pencil.

Right in the middle.

Like this.

Now push as hard as you can.

Okay.

What happens to the pencil?

It just stays in place.

It does stay in place because the forces are balanced.

Right?

Right.

Now move your fingers.

Slide them out to the ends on the opposite sides on either side of the pencil.

So one here and one here.

And now, give it some force.

What happens?

It spins in a circle.

It spins in a circle because the forces are not balanced.

Okay.

They're not working together to keep it stable.

Right.

And that the axis of this.

This is the axis.

And when you did the opposite forces, you had a rotation around an axis.

Okay.

All right.

So let's back up a little bit again.

We have gravity, right?

Acting on our beanbags.

And what force was acting on us when we did the chair?

Experiment.

Experiment on your body was that gravity?

I mean, it was gravity.

And then when we move forward quickly, that was acceleration celebration.

And then when we spun it, we had that outward force centrifugal force centrifugal force.

Exactly.

Well, now we just added torque, which is that spinning motion.

Right.

Okay.

And torque can be added by different types of forces, like with our hand to spin something or the throttle of a motorcycle, which then right.

Runs the engine and gives the motorcycle torque and and it moves it forward.

So I was just wondering, like, how do you counteract centrifugal force?

That is a really great question.

And I have another little experiment that we're going to do to kind of bring that idea home.

So I'm going to ask you what you think the key is to counteracting that centrifugal force.

Okay.

So I have this little setup here and I have a motorcycle sitting out here.

So the helmet, isn't that awesome.

All right.

So I if you're going in a circle and the bike is upright, the motorcycle is upright, okay, go ahead and just really carefully start taking this around and tell me what happens to the motorcycle.

A little faster.

A little faster, a little faster.

Keep going until it goes faster.

Keep going.

Keep going a little faster.

It starts kind of sliding.

So what happens is if you give this enough torque and acceleration, but you're upright, essentially the motorcycle is going to fling out.

Right.

Centrifugal force is going to cause it to to fling away from center.

Okay.

But if we do this.

Okay, now, now spin it around.

If this were a very, very stable toy, we could spend this as fast as we wanted to.

And it's going to stay.

It's going to stay upright.

It is going to stay upright.

So what is happening to make that happen?

Centrifugal force.

Well, centrifugal force is making it want to go away from center here, center.

And when we spun it fast, the motorcycle wanted to slide out to to the outside.

But when we do this, what did we do to it?

We leaned.

We leaned it over.

That's right.

Has to go the opposite of where it's leaning in the first.

Where it's trying.

Sorry.

This is really hard to understand, isn't it?

Because who would have thought that leaning actually keeps you from falling over in an extreme lean?

Right.

So centrifugal force is trying to make you lean one way, but if you lean the other way, that's how you counteract.

That's absolutely right.

Now, I have something really cool I'd like to show you.

You ready?

Okay.

Okay.

So here we have an example of what we just did with that experiment with the motorcycle going in a circle.

So, like we talked about earlier, we have gravity, right?

A force pulling down towards center.

Right.

Okay.

And then we have friction, which actually I'd like to introduce a couple more vocabulary words to you right now.

Friction.

Do you know what that is?

All I remember about friction is when you slide your feet.

I remember something about maybe doing an experiment with that.

Maybe rubbing your feet against the ground and with the contact.

Yes, I'd just close it down.

That's absolutely right.

So friction is two surfaces rubbing against each other.

Right.

And it causes heat and it can slow things down.

But in the motorcycle world, it actually causes a sticky patch on the tire called the contact patch.

So without friction, you cannot lean a motorcycle safely.

Okay.

Okay.

So we have the gravity working downward.

We have friction keeping the tire stuck to the track.

Okay.

They use racing slicks so there's no tread, and that helps it to be sticky air.

The hotter it gets, the faster it goes.

Okay.

And then we have that other really big force we were talking about.

Centrifugal force, right.

That wants to fling us off off track.

So you can see that this rider is leaning to counteract that force.

So just to bring that to everything is pointing kind of like away from him.

So he's going the opposite direction of where of the things are true.

That's absolutely right.

The rider has a lot of influence as to how that lean angle is going to end up helping him or her.

Okay.

All right.

So I have this other really cool thing I want to show you.

Have you ever heard of a gyroscope?

Isn't that the thing where you put it on your eye and you kind of twist it and you can see different patterns and colors?

That's a good guess.

That's actually a kaleidoscope.

Oh, it's a different kind of scope.

But I do have a gyroscope, and I would love to show you how it works and how it applies to what we've been talking about today.

Okay, perfect.

All right.

So this is my gyroscope.

Before we do our experiment with this, I have a question for you.

If you got on a bicycle and you put your hand on the handlebars and your feet on the pedals, and you did nothing, what would happen?

You would probably fall over.

You would absolutely fall over.

There is balance when your feet are down right, the center of gravity through you and down to the ground.

But if you were to put your feet up and do nothing, you would absolutely fall over.

The reason that your bike can stay upright is due to torque, gravity and acceleration.

So this demonstrates that very well.

It looks a lot like a wheel.

It is a wheel.

It is a wheel.

So this is a vertical axis.

Okay.

And I'm going to have you give this wheel some torque.

So I'll show you what that looks like and then I'll have you do it.

So you're going to grab the wheel very carefully and you're going to spin it, but not very hard.

Okay.

Not very hard.

Just to make a point.

All right.

Go ahead and spin that, but not very hard.

So what happens to our wheel if we don't if it's not moving very fast, it's going in a circle.

Right.

It wants to fall over, doesn't it?

Oh, it does.

Yeah.

So the way this applies to a motorcycle in a turn is that the faster they're going, the easier it is to stay upright.

Right.

Right.

Okay.

So if they're going slow and they're trying to go around a turn, it's not going to work.

So now I'm going to hold this.

I'm actually going to come around this way.

Now grab on real tight and give it as much torque as you can.

As much torque as you can.

Okay, now what's happening to the wheel is staying upright.

It's defying gravity.

It wants to stay upright.

Okay, so a motorcyclist now has torque and acceleration.

Gravity and centripetal centrifugal force causing this wheel to want to stay upright because they're going very fast.

So they actually have to use their body to lean in to the curb so that they don't get flung off a motorcycle.

But they have to keep spinning it over and over again.

They can't stop.

That's right.

All over this example, it decays, right?

The spinning decays.

And we don't have that phenomenon of defying gravity.

But of course, when you're riding a motorcycle, you're constantly giving it gas.

So it's accelerating all the time.

Right.

And that's what helps them be able.

So that spinning of the wheel causes the friction we were talking about earlier, which gives them a contact patch.

So there is one force I didn't mention that is acting on the motorcycle.

And it has to do with the with friction.

And that is centripetal force and that is a force acting towards the center.

Okay.

But the bigger force, the faster the wheel goes, is centrifugal force, wanting to force the motorcyclist out from away from center.

So they have to give input with their body.

They actually have to lean and put their their body off the side of the motorcycle and lean the bike into the turn in order to be safe.

Kind of like what we saw in that picture you had earlier where the room is touching the ground that's they're leaning.

That's absolutely right.

And if you remember, we talked about how they can lean so far that the side of their bodies can actually skim the ground.

64 or 65 degrees is a very big angle.

And so another thing that keeps them safe is their safety gear.

So I wanted to show that to you because we're talking about how far they can lean and they have to keep themselves safe.

So safety gear.

I'm going to show you this suit first.

Guess how much?

Here, hold this.

Tell me how much you think it weighs, like 50 pounds.

I know it feels like 50 pounds An entire suit can weigh over 40 pounds boots and helmet and all.

So most of the suit is made of leather.

Okay.

But all of the points where their body might potentially skimmed the ground are reinforced.

So you see reinforcements on the shoulders so you can feel those are really hard.

Oh, yeah.

On the elbow.

They're kind of like shin guards for soccer.

Absolutely.

And they can be replaced, too, if they get worn down.

And then, of course, they're knee because they're their whole body is actually off the motorcycle.

So their knee can skim the ground as well.

And of course, it's made to be aerodynamic, but it's very heavy, very protective.

All right.

So in addition to their suit, they have boots and of course, their boot is reinforced on the toe and the heel because the side of their body that's nearest the track.

You know, of course, their toe can can skin the ground as well.

And that's not all.

Here is an example of a riding glove.

So you can see that the knuckles and well, both sets of knuckles on the top of the hand and the fingers are both reinforced.

Last but not least, is what I think is the most important part of the safety gear.

And that's the helmet.

So have you seen a helmet like this before?

I have.

Okay.

This is a full face helmet.

So it covers their chin and everything.

It's got the visor to protect their their face from the sun.

Bugs and debris from the from the track.

How can they see through it?

Well, it is just a sun visor.

It looks very dark, but, you know, it's just like wearing a pair of sunglasses.

Yeah.

So same thing.

And then, of course, it's very hard on the outside and extremely cushioned on the inside, so it can take a really good impact.

And one of the things I like to tell my students is to look for this sticker on the back of a helmet, because if a helmet is not dot certified, then it's not the safest helmet.

And of course, in Alabama, it's the law to wear a helmet when you're riding motorcycles or dirt bikes.

Right.

So we want to make sure we have a safe helmet.

So if you want to take a look at that, this can help you see.

Yeah.

Also, I see a lot of designs and colors on their clothes, in their helmet.

Yeah, that's a really good point, actually.

Those are their sponsors.

So people that race cars or motorcycles, they have people that sponsor them so they can advertise for them.

And then they, of course, give them funds r their racing career.

So all of the designs you see on there, all the different names and things, those are the those are the sponsors for the racer.

And if you have like teams, do they have like team colors or.

Sometimes, yeah.

I mean, I do think that each individual racer and driver has their specific colors for their car or their bike.

Mm hmm.

That's really cool.

Yeah.

Okay, so we've talked about their safety gear.

We've kind of culminated all of the information that we learned.

But let's go ahead and review really quickly.

I can go ahead and put this down for you.

All right.

So we talked about the force of gravity, right?

The fact that there needs to be balance maintained.

So when a motorcycle rider is on his bike, his equilibrium is through his body and down through the middle of the motorcycle.

Mm hmm.

Now, when you add acceleration to that, you now have opposite forces.

Right.

So what happened when we accelerated around a corner?

What happened to your body?

I leaned right.

Your body wanted to flee away from the center.

So what did you do to get equilibrium back on balance the other way?

That's absolutely right.

That's absolutely right.

So when our chair was going around in a circle.

Same thing happens with a motorcycle.

We are experiencing centrifugal force.

And the faster they go, the the greater that force.

So they need to counter that force by leaning away from it.

Right.

And creating balance.

Thank you so much for showing me around today.

I've learned so much about physics and about motorcycles and forces and all that kind of stuff.

Well, it was my pleasure to have you here.

Thank you so much for joining us at Barber Motorsports Museum.

Oh, yeah.

I would love to have you back any time.

And maybe next time you're here, we can get you out on the track.

And maybe get me one of these so I can work on that.

Okay.

And that's all for now.

on Alabama STEM explorers, we'll see you next time.

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Alabama STEM explorers is made possible by the generous support of the Holle Family Foundation, established to honor the legacy of Brigadier General Everett Holle and his parents, Evelyn and Fred Holle.

Champions of Servant Leadership.