- Are you feeling curious?

Isn't that cool?

Today on "Curious Crew."

- Whoa!

- It balances!

- It's steady as she goes.

Yeah, this is not easy.

In an episode that's a little off balance.

Oh!

Yeah, there it's gonna fall over.

- [Announcer] Support for "Curious Crew" is provided by MSU Federal Credit Union.

From sweet peas to teens, MSUFCU offers you accounts that grow with children.

With financial education, gaming apps, and events, MSUFCU provides the tools and resources to make learning about finances fun and interactive.

Also, by the Consumers Energy Foundation dedicated to ensuring Michigan residents have access to world-class educational resources.

More information is available at consumersenergy.com/foundation.

Consumers Energy Foundation, supporting education and building sustainable communities in Michigan's hometowns.

And by viewers like you.

Thank you!

(cheerful theme music) - Hi, I'm Rob Stevenson and this is.

- [All] "Curious Crew!"

- Welcome to the show, everybody.

We always like to start every episode with a couple of discrepant events because discrepant events stimulate.

- [All] Curiosity!

- That's exactly right, and I've got some fun ones for you today.

First of all, it's going to start with an ordinary piece of oak.

And the interesting thing about this piece of oak is I've drilled a hole in it.

And in fact, on one end, I cut a 45 degree angle.

Now, I'm gonna ask you a question, Ian.

I'm gonna put the flat edge down like this.

Do you think I can balance this board on the table?

- I think you should be able to.

- (laughs) I should be able to.

He doesn't trust me.

Okay, it does balance.

Now, what if I turn it over on the 45 degree angle?

Do you think that will balance?

- Won't it just fall onto the table?

- Yes, it clearly will.

So that will not balance, but I would like to try to bring this two liter soda bottle into the system.

I'm gonna take the top of this, place it through the hole in the board.

So Ian, do you think the entire system will be able to balance?

- I don't think so.

- Let's take a look.

Ooh, look at that.

Okay, I can get it to balance as a system.

Does this get any wonderings going for anybody?

Anybody have any wonderings?

What's your wondering, Rishabh?

- What will happen if you push the bottle?

- That's a really good wondering, but I'm gonna make you wait and think about that.

I'm just gonna slide that over just a little bit and share something else with you.

I've got a ruler, a hammer, and a piece of string, and the thing to notice is both the ruler and the handle of the hammer go through this piece of string.

And what I'm going to attempt to do is see if I can suspend this system on this little acrylic table.

Oh, yes.

So we've got some interesting discrepant events.

Now, I'm gonna invite three of you to do a little scientific modeling, using your background knowledge, evidence throughout the show to revise your thinking.

So who would like to do a little modeling moment, try to explain these at the end of the show?

Who'd like to try this?

Okay, Adia, Janellyn, Kah'reice, you guys are gonna be working on that.

So what do you think we're gonna be investigating today?

Anybody have a guess?

Tauren, you have a thought.

- Is it balance and maybe stability?

- Yes, we are talking balance and stability.

Excellent.

You're gonna wanna stick around.

We have a lot of great investigations that you can try at home.

(casual music) - Okay, let's see if we can figure this out.

- I seen a guy on the internet who can balance almost anything: a motorcycle, a rock, you name it.

- That's amazing, but they probably aren't very stable.

- Yeah, I was actually thinking the same thing too because similar to Dr.

Rob's discrepant events, the objects are able to balance, but how stable are they?

I wonder how much force it'd take to knock them over.

(funky music) - Although we don't think much about it, balance is what keeps us from tipping over or falling down, and our senses and muscles work together to make that happen.

Of course, there are times when we lose our balance or have a harder time keeping our balance like when we have on a really heavy backpack.

But what about objects that aren't alive?

Why are some objects more stable than others?

A toddler sippy cup is a good example.

It is usually pretty stable and takes a bigger disturbance to knock it over.

Whoops.

Now, if we wanna understand balance, we have to think about stability, and one of the interesting things about stability is we can classify it into three different categories: something that's called stable equilibrium, unstable equilibrium, and neutral equilibrium.

Believe it or not, I have three groups of items here and they're going to be representing each one of these groups.

Now Tauren, here's a wondering for you: which group would you guess is gonna be the most stable if I push on them?

- I think group one.

- Group one, okay.

So if I apply a slight disturbance for these things, you're noticing they just stay put.

And that makes sense.

We've got a low center of mass and a big base of support.

You are correct.

This is stable equilibrium.

Now, if we look at the next group, what will happen if I start poking at these, Rishabh?

- They're gonna fall since their center of gravity won't be supported by their base anymore.

- Okay, so we have a high center of gravity and you are correct.

Ah!

They're gonna fall over.

These would be example when they were starting as unstable equilibrium because they're gonna tip over.

The third group is really interesting though.

You'll notice if I push on these objects, they roll around.

They don't fall over, but they roll around.

This is a continually supported center of mass and a wide base of support.

But because they roll, we refer to this as neutral equilibrium.

Okay, now we are gonna apply our thinking.

I have in front of me three little cute infant toys and infants have a hard time with fine motor control and grasping things, so we want things that will roll around and bounce.

And so if I bump these things, they roll around and they stand upright again.

So Tauren, which group might these belong to?

- Hmm.

Maybe group one?

- You are correct.

It is group one.

Because even though they roll around and move, they will end up standing upright yet again.

Pretty interesting.

Now Rishabh, can you tell me what you've got there at home?

- We have some cans which we plan to fill 80 to 100 millimeters of water, and we're trying to do this to balance it when we put it at a about 45 degree angle.

- Okay, excellent.

I've added some water in here and we can actually get it to balance.

And what's really interesting, if I give it a gentle disturbance, it will roll around, kind of like neutral equilibrium.

Let me see yours.

Can you guys get yours to balance real quick?

You set yours up and I'm going to set up one more myself.

Oh, look at that.

Oh, well done.

So you could disturb yours a little bit there, Tauren.

I saw that Rishabh's is like swinging around.

Excellent job.

If you can put your cameras up for just one second, I wanna show you one more.

This can's really large.

Because it is so large, I'm gonna add 220 milliliters of water.

Now, the interesting thing is a can that's empty will not balance on edge because the center of mass, it's not in line with the support underneath.

But if we can add enough water, we can lower the center of mass and actually support it on edge.

Isn't that amazing?

Look around your house.

See if you can find examples of stable, unstable, and neutral equilibrium.

We saw how the empty can was really unstable on its edge, and it wasn't until we added water that we could get it to balance.

Well, imagine a chair sitting on the floor.

Its four legs provide a good base of support, so it's really stable.

But what if we tried to balance the chair on only one of its legs?

That would be unstable because even if it were to balance, a slight touch would knock it over and certainly we couldn't sit on it.

A single leg is too small an area of support, and if the center of the chair's mass is on either side of that support, it will tip over.

See what I mean?

So here's a little investigation you can try at home.

I've got a barbecue skewer that I've pierced through three marshmallows, and I've been trying to get it to balance on one finger.

I keep sliding that center marshmallow one way or the other trying to get it to balance.

Adia, can you think of a way where I can make balancing this marshmallow system easier?

- You can add more marshmallows to the bottom.

- Oh, that's actually a really good idea.

And I love how you said the bottom and not going up 'cause if I add more on the top, that's gonna be a problem.

I actually happen to have some of those.

So here again, I've got three marshmallows pierced through a barbecue skewer, but notice we've added some additional marshmallows underneath.

This is actually much more stable.

Now you might be wondering why would it make that much difference?

Well, we're adding mass to the system, and if we lower the center of gravity, especially underneath the support of my finger, we have a much more stable system, and we would refer to this as stable equilibrium.

Now, I've got another wondering for you guys.

I'd like to see if you can balance a pencil on its point.

Yeah, this is not easy.

Okay, but we've got a trick.

Ian, describe what we can do to make this work.

You guys can slide some materials in 'cause I know you have some there at home as well.

What can we do to make this easier?

- So one of the things that we can do is just like with the marshmallows by adding mass to either side of the pencil.

- Okay, and so we've got a piece of wire around this pencil, and we're adding just a couple of clothes pins on there.

And if we do that, we can actually change the mass in the system, lower the mass quite a bit even underneath the point of the pencil.

Can you guys get yours to work?

- Yeah!

- Excellent, yeah!

And Adia's gonna put hers right on a Popsicle stick.

I'm gonna do the same thing, see if I can get that balanced on a Popsicle stick.

Now it seems strange that this should be able to balance, but it's all about where the mass in the system is and having a lower center of gravity increases stability.

In fact, we can even tap on this and it will stay put.

This reminds me of this fun little toy that I've got.

It's sort of similar to the pencil on point.

He's standing on one foot on this little pedestal, and he's holding this balance beam that curves down and has these weights on the bottom.

But notice this is incredibly stable.

I can really push it, swing it.

It'll bob around and bounce.

But eventually when it stops, it will still be standing upright.

This is a great example of stable equilibrium.

When we want an object to be more stable, we might choose to widen the base of support or lower its center of mass, like our pencils on point.

The clothes pins added mass to the system, lowering its center of gravity, but a wide base makes a big difference too.

The girl's center of gravity is like a concentrated force pulling down on the center of her mass.

If that concentrated force is centered over her feet, she is more stable, but simply by shifting her weight to one side makes her less and less stable.

Oh, careful.

(catchy music) There are other creatures that have amazing sense of hearing, and they use echolocation.

- [Audrey] In the "Sense of Hearing" episode, Aaron put on a blindfold and he was trying to tell where we were.

Aaron.

- Aaron.

- I had no idea how much my eyes connect to my ears.

- Aaron, remove your blindfold and look where I am.

- Whoa.

- (laughs) Okay.

- It was really cool to see that our ears are very dependent on our eyes.

- Try this yourself.

See how well you can echolocate.

It's pretty cool.

(sports fanfare music) - [Announcer] Stem challenge.

- So have you had fun exploring balance and stability so far, you guys?

- [All] Yeah.

- Excellent, we have a really fun Stem Challenge that's going to incorporate both balance and stability.

You have a lot of materials at your disposal, but your task is to somehow balance this ball 12 inches above the surface of your workspace using these materials.

So you guys ready to start?

- [All] Yeah.

- Let's try it.

- So I'll need lots of triangles for stability.

We have to try to get a squishy baseball a foot off the ground, and all we have to use is straws, toothpicks, gumdrops, and marshmallows.

- Ooh, I have an idea.

I chose gum drops to provide a somewhat wide base for my baseball to lie on.

It's not gonna work.

Ah, I got it.

Well, I'm gonna maybe use some toothpicks like this to wedge the baseball in, so maybe that will work.

- I love the marshmallows.

You saw nothing.

- I did snack on a few gumdrops.

- Nope, that's not strong enough.

- Whoa!

- Don't fall apart on me.

Ah!

My advice for somebody who would try this experiment at home is look around at all the other structures that are around you, like bridges or tall buildings, and see what their base is made of.

Some bridges are made of triangles and triangles are actually very stable.

- It balances!

- I think this experiment is a great way to demonstrate how stability and balance works.

Yes!

It works!

Oh!

- Ah!

- So it looks like you're just about finished, and I'm curious.

Do you think these structures can handle a slight disturbance?

Ian, do me a favor, lift yours up.

So we've got some gumdrops going on there, and you used a triangle base.

Okay, let's see.

Do you think yours can handle disturbance?

- I'm pretty confident it can.

- Let's try it.

Wow, so we've got some stable equilibrium there.

It actually stood back up again.

That was impressive.

All right, now Rishabh, yours has been very exciting to watch as you've been building, and I see this beautiful structure up on top.

Do you think yours is gonna be able to handle a slight disturbance?

- Uh, no.

- Oh, we have to try it.

Give it a little disturbance.

(Robert laughing) Well done.

Now the tricky part in a design like this is we have a really high center of mass, which makes things very unstable.

Okay, how about yours, Tauren?

Will yours be able to handle a slight push?

What do you think?

- Yes, I do.

- Okay, let's try it.

- Oh my goodness, okay.

So we had some examples of stable equilibrium and unstable equilibrium.

That's what I would expect to see.

Try making your own balance and stability structure.

It's really fun.

The crew did a great job with their structures and had to think about the mass of the ball to be able to balance and support it.

A larger base is one solution to make structures more stable.

We can see this in racecars, too.

Formula 1 cars have a broad base and sit very low to the ground to lower the center of mass and improve stability.

That's really important to prevent the car from rolling when you go into a curve at over 200 miles per hour.

Now that's a great stable design.

(casual music) - We have another interesting investigation with balance and stability.

Kah'reice, what have you got set up there?

- Well, I have my glass flask, my rubber ball, two toothpicks, two forks, a foam ball and some corks.

- And you've got that whole system totally balanced on a single toothpick, don't you?

What'll happen if you tap on one of the handles of the forks?

Will that fall?

- We'll see.

- Oh!

Yours is really pretty stable.

Janellyn, how can these things stay balanced?

- Well, the center of gravity is actually being offset by these forks that are in the opposite direction.

So the supporting point is right here at the tip of the toothpick on the rubber ball.

So because these are going the opposite direction of where the system is, it's able to stay balanced.

- It's amazing, I've got some tape on my styrofoam ball, but I also was able to add a couple of layers of corks on top.

I'm not sure if mine is quite as stable as Kah'reice's, but I'm gonna give it a whirl.

Oh!

So that actually is staying put.

So we have this low center of mass and gravity because of the handles.

So we can offset that entire system getting the entire thing balanced, which is amazing.

Now I've got a stick here and a wire, and I'm just gonna place this wire on the end of this stick and attempt to balance it right at the center of gravity.

So you can see I've found the center of gravity.

I've got this leg hanging down, this leg hanging down, and so the mass is moving down in the system so it stays put.

Where this gets more complicated is I wanna see how many additional sticks I can add into the system by supporting the center of gravity.

And each time I do this, you're gonna notice that the stick leg is a little bit longer.

Now that kind of makes sense.

We need more and more mass to be able to deal with the entire mass in the system and support the center of gravity.

Now, I'm getting a little nervous 'cause this is getting really hard to hold.

Oh boy.

I think I better get it on the stand.

Yes.

Now, watch closely.

If I remove the wire, the entire system is going to fall apart.

Let's see what happens.

Isn't that cool?

So they all go one at a time.

This is a great example of unstable equilibrium.

In our investigations, we balanced and supported the objects from underneath, but we could have supported them from above as well.

A mobile is a great example of a hanging balanced system that can remain balanced even when a force acts on it, like a gentle breeze.

The challenging part about making a mobile is to evenly distribute the weight around the mobile so it stays level.

One trick is to build from the bottom up and find the center of each support before adding another level.

Curved supports are also more stable than straight ones because they lower the center of mass.

That marvelous mobile is beautifully balanced.

(bright music) Are you curious about careers in science?

Hi, I'm Genesis, and today I'm here with Rebecca Gulbransen.

Rebecca, can you tell me where we are and what you do?

- Yeah, we are at Yoga State in East Lansing, Michigan, and I am a yoga instructor.

I teach here in the studio and I also teach standup paddleboard yoga out on the water.

- What aspects of Stem are a part of yoga?

- Stem is central to the physical aspect that you receive when you are practicing yoga.

Once you have your feet settled, lift your arms to the sky.

- What are some of the health benefits of doing yoga?

- Some of the best health benefits from doing yoga are definitely feeling peaceful, feeling calm and centered, but also there's a really great energizing spirit that comes with yoga.

Being able to move your body physically in such wonderful ways helps balance your body, and it also helps center you emotionally.

- I exercised my body and mind today doing yoga with Rebecca Gulbransen.

Explore your possibilities.

(bright music) And now, back to "Curious Crew."

- Hi, Tauren.

- Hello, everyone.

(casual music) - So with the balancing bottle, the center of gravity must be supported.

- Yeah, I think so too.

The center actually lined up directly over the board, just like with the uncanny cans.

Otherwise, the bottle would tip over.

- And with the hammer, the lower mass is more stable, just like with the marshmallows and the sticks.

- Right, and the hammer was still supported by the ruler, so it was able to hang suspended under the table.

- So have you guys had fun exploring balance and stability today?

- [All] Yeah!

- Awesome, now I know several of you have been hard at work thinking about these phenomena from the beginning of the show, and they might have thrown you off balance a little bit, (drum set stings) but what did you think about this balancing bottle, Kah'reice?

- Even though it looks like it should fall, it doesn't because of the system of gravity being supported.

- Alright, so we've got this center of gravity right here that's actually going to be supported.

And in fact, if I were to draw an imaginary line that goes straight down towards the table, this would be the line of gravity, and if that line intersects with the base of support, we have a balanced system.

Nice job.

So let's think about its stability.

Adia, what do you think's gonna happen if I push on this bottle?

- I think it'll tip over.

- You think it's gonna tip over?

Okay.

So if I push it this way, it's not so bad, but if I push it this way... Oh!

Yeah, there it's gonna fall over.

This is an example of unstable equilibrium.

We get it balanced, but a slight disturbance will knock it over.

- Can you try that other bottle?

- Okay, you read my mind.

I'm gonna try the other bottle.

Now notice the difference between these two first.

So we've got this one that's a lot more slender and it's got a longer neck.

The interesting thing about this bottle is it really is gonna depend where I position it to get it balanced.

If I don't get it just right, we actually have the center of gravity too far out and it's gonna tip over.

Now, if I wanna make this more stable, I might need to make some adjustments.

I might need to change where the hole is.

I might need to change the angle on my miter cut, or I might even need to use a thicker board to create a balanced system.

Good thinking, you guys.

All right, what about this hanging hammer, Janellyn?

- The mass from the hammer is in the hammer's head, so the position of the hammer head is really important, but it's stable because the center of gravity is directly in line underneath the ruler.

- Great thinking, everybody.

The other thing that we have to think about is a slight disturbance is gonna knock this down, so we've got another example of unstable equilibrium.

Now I wanna show you another variation of this.

This is gonna require a bottle with a string on it, and I'm going to try to suspend this from a wooden match.

This one is quite the balancing act.

And there it is, oh my goodness.

A single matchstick, but the same rules apply.

We've got a lot of the mass underneath that base of support, but it's probably not very stable, is it?

This will easily fall down with a slight disturbance.

When we start thinking about balance and stability, it's involved in a lot of the games we play, a lot of the sports we participate in, which makes this science concept particularly interesting and fun.

So remember, my friends, - [All] Stay curious!

- And keep experimenting.

Get your curiosity guide and see more programs at wkar.org.

- [Announcer] Support for "Curious Crew" is provided by MSU Federal Credit Union.

From sweet peas to teens, MSUFCU offers you accounts that grow with children.

With financial education, gaming apps, and events, MSUFCU provides the tools and resources to make learning about finances fun and interactive.

Also, by the Consumers Energy Foundation, dedicated to ensuring Michigan residents have access to world-class educational resources.

More information is available at consumersenergy.com/foundation.

Consumers Energy Foundation, supporting education and building sustainable communities in Michigan's hometowns.

And by viewers like you.

Thank you!

- Now, the last... (laughs) I knew that was gonna happen.

Okay, Adia, can you push... Oh!

(laughs) - Hey!

It fell!

Now time to fix you, you poor object.

(soft piano music)