Newton's Apple; No. 1201

<v Host>For KTCA TV St. Paul, Minneapolis. <v Host>Next on Newtons apple. <v Rebecca Lance>You just keep running till the earth falls away from our feet. <v Peggy Knapp>Oh, girl, this is great. <v David Heil>How is that possible? <v Nancy Gibson>All right, bring in the animal. <v David Heil>This is great, right here in the warehouse,. <v Nancy Gibson>I know, can you imagine that <v Host>Newton's apple is made possible by a grant from 3M, the company where creative people find ways to make our world even better, 3M innovation. <v Host>Welcome to Newton's Apple, the show that answers your questions about science, nature, technology and the world around you. Here's your host, David Heil.

<v David Heil>As you can see, we're about to kick off a whole new season, answering even more of your letters. And the very first story of the season begins with a question from Henry Labonte of San Rafael, California, who writes, I've always been fascinated watching hang gliders fly through the air. How do gliders fly without engines? This is going to keep you in the air? <v Guest>Sure, no problem. <v David Heil>You know, usually I'm the one that gets to do these life threatening kinds of stories. I've jumped out of an airplane, I've climbed sheer cliffs, even rolled over in a stunt car. So this is one story I'm just sure our field reporter, Peggy Knapp would love to do. <v Peggy Knapp>My favorite dreams have always been flying dreams. Imagine the feeling soaring high on the air currents with only the Eagles as companions. Now I want to make that dream a reality, which is why I've almost decided to try hang gliding. You see, I've always wanted to fly like a bird, but not if it means jumping off a cliff. <v Peggy Knapp>I need to know the science flying. I need to know the science of not crashing. I need a physicist. Yeah, like one's going to fall out of the sky.

<v Peggy Knapp>But one did. Ilan Kroo, a professor of aerodynamics from Stanford University. What are the odds? <v Peggy Knapp>Ilan, there's a noticeable absence of a motor on this. What keeps them in the air? <v Elon Kroo>Well, they are, in fact, coming down. If there weren't any wind. There, this kind of flying is a kind of controlled falling. They're coming down at how much falling? Well, maybe something on the order of two miles an hour in steady state with no wind. <v Peggy Knapp>Well, that's not so bad. <v Peggy Knapp>Flying a hang glider is kind of like throwing a huge paper airplane and not letting go. You see, air has mass. And if the gliders wings hit that air at the right angle with enough speed, they'll ride on top of the air in a downward path to the ground. So the motor of a hang glider is gravity. <v Elon Kroo>What keeps it in the air is a combination of lift, which keeps it from falling, from accelerating toward the ground. <v Peggy Knapp>Good.

<v Elon Kroo>And gravity, which keeps it moving forward. Modern hang gliders can go down one foot for every about 13 feet. They go forward and this is a measure of their efficiency. <v Peggy Knapp>This thirteen to one ratio for hang gliders is also called its lift to drag ratio. And the higher the ratio, the farther it will glide. But first you have to get airborne. Now, just for comparison, at 350 tons, a Boeing 747 needs an air speed of 180 miles per hour to get off the ground. A hang glider with its pilot only weighs between 200 and 280 pounds and takes off at about 20 miles per hour. But that's still faster than I can run. So how do I get off the ground? <v Elon Kroo>The key idea is to balance the aerodynamic forces. And you don't need to solve any equations to do this. You just need to be moving with respect to the air at a certain speed. For hang gliders, it's about twenty to twenty five miles an hour. So that means either you have to run at 20 miles an hour or you have to have 10 miles an hour of wind and run at 10 miles an hour, which is pretty easy to do. <v Peggy Knapp>The wind changes everything for a hang glider since the glider descends at about two miles per hour. All you need to do is find wind moving upward at two miles per hour to stay in the air, which is the whole point. Finding lift is a cat and mouse game that pilots love to play. And there was one more question I just had to ask.

<v Peggy Knapp>Just out of curiosity, how safe is hang gliding? <v Elon Kroo>Well, safety is certainly a concern in any kind of aviation. And many different steps are taken to make Hangu letters as safe as possible over the years has been a great deal of testing, both structural testing and aerodynamic testing. And certainly for beginners, we start out not by jumping off a cliff, but on a bunny hill with training wheels. <v Peggy Knapp>Hey, I'm OK with this. Really flying close to Mother Earth is just fine with me. But before I could fly, I had to assemble my aircraft, which a good pilot can do in about 15 minutes. <v Rebecca Lance>Meet Mr. Glider. <v Peggy Knapp>My teacher is Rebecca Lance, certified instructor and registered nurse. I think a good combination and on tactical support is Pat Dunovant of Mission Soring Center in Milpitas, California. Together, hopefully they can get me off the ground. <v Rebecca Lance>Now before you launch a glider, there's one very important thing you have to do. So we're going to run through that. It is very important. And when you launch that, you be attached to the glider.

<v Peggy Knapp>Well yeah. <v Rebecca Lance>The glider, the glider will fly just fine without you, but you're not going to fly so good without it. <v Peggy Knapp>Securely fastened to the frame. I'm free to swing in any direction. This is why they call it hang gliding. <v Peggy Knapp>Hang check. <v Rebecca Lance>Hang check. <v Peggy Knapp>Once in the air, the pilot steers by positioning her body center of mass below the glider swing to the left. The glider turns to the left. Pull your body forward. It speeds up and dives. <v Rebecca Lance>Keep the wings level. Take a step or two. Keep the nose down. <v Peggy Knapp>They say you have to walk before you can run and run before you can fly, and believe me, I was doing a lot more running than flying. Clearly, this wasn't working, but with just a little more wind, a bigger glider to catch that wind and a lighter touch on my part, it finally happened. <v Rebecca Lance>Beautiful.

<v Peggy Knapp>I'm flying! How come I'm doing that. <v Peggy Knapp>This is getting cooler and cooler, <v Peggy Knapp>I had a taste of it now I just had to fly, really fly. But how? <v Kari Castle>I'll take you up. <v Peggy Knapp>Of course. Flying tandem. The woman in the big pink glider is Kari Castle, certified tandem instructor and the women's world record holder for long distance flight. I am in good hands. <v Kari Castle>So what's going to happen is you're going to be standing next to me and you're going to put your your left hand here and your right hand on this little handle, OK? When we start running, it doesn't matter which way you start with, it doesn't matter. The main thing is when I say clear, which is our signal to run is that we both move at the same time together. Basically, we're doing a bit of a dance. And as long as you dance with me and move with me as a unit, we're going to be flying away beautifully. <v Peggy Knapp>I take it you're leading. <v Kari Castle>I lead the dance, yes and then we pick the glider up. OK, everything feels really good. I'm excited. <v Peggy Knapp>The wind is blowing perfect.

<v Kari Castle>Absolutely perfect. And I say, Are you ready? <v Peggy Knapp>I'm ready. <v Kari Castle>Alright OK? And wing people, I say, get away from my wing. OK, I got it clear. And we run. <v Peggy Knapp>And then we just keep running. <v Kari Castle>And we just keep running till the earth falls away from our feet and we are flying. Yeah. whoo, we're going to have fun. <v Peggy Knapp>When Kari felt I was ready, we got into position on the ridge nineteen hundred feet above the valley below. Then we waited for the wind. <v Kari Castle>That feels pretty good. Are you ready? <v Peggy Knapp>I'm ready. <v Kari Castle>Are you sure? <v Peggy Knapp>I'm ready. <v Kari Castle>OK, Clear. <v Peggy Knapp>I'm ready, whoo! <v Peggy Knapp>My heart was in my throat as fast as the ground fell away from my feet, all I could do was hang there and leave the flying to Kari. Then came the time for me to open my harness and get into my flying position. Did I mention that Kari's harness has a parachute. <v Kari Castle>Oh, there she goes.

<v Peggy Knapp>Oh, girl, this is great. <v Peggy Knapp>Almost immediately, Kari started looking for lift when she finds it, her varitometer beeps, telling us we're going higher. <v Kari Castle>Today, on a day like today, we're hitting only thermal lift, and what thermals are- you felt that little bubble, it is little warm balls of air going up. <v Peggy Knapp>Thermals are like invisible hot air balloons. During the day, the rocks below us absorb the sun's energy and warm the air above, which rises up in a column. When pilots find thermals, they circle like hawks to stay inside when the air felt pretty stable. Kari, let me take the controls. I couldn't believe it. <v Kari Castle>Yeah, you're doing this on your own, My hands are free. You're flying. <v Peggy Knapp>I'm flying. <v Kari Castle>See no hands. <v Peggy Knapp>[screaming] Eat your heart out.

<v Kari Castle>Let's go that way, turn it to the left. <v Peggy Knapp>Then sadly, it was time to land. <v Kari Castle>You go ahead and get up right,. <v Peggy Knapp>Feet out. <v Kari Castle>Feet out <v Peggy Knapp>Hang gliders are the only aircraft that land like birds. And it's a pretty neat trick. Just before landing, the pilot pushes forward on the control bar and sharply increases the gliders angle of attack. The wing collides with a massive air, slowing the glider and dropping the pilot on his feet. If it's done right, it's a thing of beauty. <v Kari Castle>Get ready, you ready and stop. No worries. <v Peggy Knapp>No worries, perfect landing, yes! <v Peggy Knapp>[Music plays] Which of your voluntary muscles get the greatest day to day work out? <v Guest>Your tongue like your your jaw muscles.

<v Guest>Gluteus maximus. <v Guest>Heart, I think your heart. <v Peggy Knapp>It's your eye muscles, the heart is a good guess. However, that's an involuntary muscle that you can't control. The muscles of the eyes are the busiest voluntary muscles. They've been known to move about 100000 times in one day. What a workout. <v David Heil>As you know, we get all kinds of mail here at Newton's Apple, but this particular letter is very unusual. Somebody sent us a letter written on a wooden board. Let me read it to you, dear Newtons apple. <v Dr. Bruce Dan>Excuse me. <v David Heil>Well, hi, Bruce. How are you doing? <v David Heil>This is Dr. Bruce Dan, our resident medical expert. You're going to get a kick out of this letter. You got a background in medicine. Listen to this, dear Newton's apple-. <v Dr. Bruce Dan>Excuse me, David-. <v David Heil>Bruce, we have a show to do. <v Dr. Bruce Dan>You have to hold it like this. <v David Heil>You have to hold the letter like, whatever you say Bruce. We're going to get moving here. OK, dear Newton's Apple. How can karate experts break boards without hurting their hands? What is going on here? <v Dr. Bruce Dan>Well, let me introduce you to somebody. This is Dr. Mike Dunphy's, who is a black belt in karate.

<v David Heil>Not sure I should shake his hand. <v Dr. Bruce Dan>He's here to answer your question. David. <v David Heil>Welcome to the show, Mike. <v Dr. Mike Dunphy>Thank you. <v David Heil>Got here just in the nick of time. I didn't hurt your hand a bit. <v Dr. Mike Dunphy>Not at all. <v David Heil>So how can you break a board with your bare hand and not have a damage? <v Dr. Mike Dunphy>As a matter of fact, I don't only break boards, but come over here. We can break concrete. <v David Heil>No way. Three concrete bricks. <v Dr. Mike Dunphy>There is three concrete blocks set up on two cinder blocks. And I'm going to take my hand and put it through the concrete blocks. <v David Heil>Without hurting your hand. <v Dr. Mike Dunphy>Well, I hope so. <v David Heil>Oh, good grief, you did it. How is your hand? <v Dr. Mike Dunphy>Well, it's OK,. <v David Heil>Sure enough, it's amazing. Can we get this in slow motion? This is phenomenal. Look at this. Now, look at that. Is he and his scrunches up on the bricks. And then, sure enough, they all just all three crumble right under there. I'm going to get a closer look so we get a little bit of scraping here from the brick. But that's it. You can move it. <v Dr. Mike Dunphy>Sure. <v David Heil>How is that possible? <v Dr. Bruce Dan>Well, actually, for two reasons, David. One is that the absolute marvelous construction in anatomy of the human hand. The second is the amazing amount of power and energy that a trained karate professional can exert.

<v David Heil>OK, let's start with the hand. This is the part I'm familiar with. <v Dr. Bruce Dan>Well, to explain I got to go see our old friend dead Earnest. <v Dr. Mike Dunphy>OK, guys see you in a little bit. <v Dr. Bruce Dan>OK. Here we are with Newton's Apple skeleton. <v David Heil>All right, now, if I remember right when Mike struck the brick, he did it with this part of his hand, right? <v Dr. Bruce Dan>Right. That's called the fifth metacarpal, one of the five bones of the hand, the five metacarpal bones. And actually, it took the brunt of all the force. But the bone itself, bone is 40 times stronger than concrete. <v David Heil>Bone is stronger than concrete? <v Dr. Bruce Dan>It actually is. Yes. <v David Heil>Wow I had no idea. You know, it still, though, even even though it's stronger, it looks kind of vulnerable here. When you strike it against the concrete, it seems like it would break. <v Dr. Bruce Dan>Well, can you feel the metacarpal bone in your hand? <v David Heil>Yeah, I can feel it right there. <v Dr. Bruce Dan>Now, make a fist for me. OK, what do you feel? <v David Heil>I don't feel the bone anymore, it is surrounded by the muscle, <v Dr. Bruce Dan>Right, which provides a cushion. Matter of fact, it's the muscle, the tendons, ligaments, all the other soft tissue, the hand provides a cushioning effect, very much like the springs in sort of dead ernie's hand here there's a springiness to hand, a bend and a give it's elastic. So when you hit something solid, it disperses the energy within the hand. A brittle substance breaks. <v David Heil>Even though there's all this sort of springiness in the hand when Mike strikes his hand against the brick. How come it doesn't just bounce off like mind does?

<v Dr. Bruce Dan>Well if you hit it as softly as that it certainly would. But a trained karate professional exert so much force that he actually can break an object in the hand survives. <v David Heil>How much force are we talking about here? <v Dr. Bruce Dan>Well, let me show you. <v Dr. Bruce Dan>Hey, Mike. <v Dr. Mike Dunphy>Well, hi, guys. <v David Heil>Wait, wait, wait a minute. Wait a minute. We started out talking about karate and now we're into weightlifting. <v Dr. Mike Dunphy>Well, actually, we've set up a demonstration, guys, to help you understand the kind of force that's generated when my hand struck those bricks earlier. What we have here is four friends from high school, senior high school, the weightlifting team, they're going to pick up this barbell and put it on top of three bricks stacked exactly as we had them earlier. Ready, guys, let go. That's the kind of force we're talking about. <v David Heil>Look at that. Wow. I just broke them clean, didn't it? Very similar to when you hit it with your hand. <v Dr. Mike Dunphy>Exactly. <v David Heil>And Mike, how much weight do we have on this thing? <v Dr. Mike Dunphy>Well, David, this is six hundred and seventy five pounds, <v David Heil>Definitely more than I'm going to lift. You're talking about getting six hundred and seventy five pounds out of your hand. <v Dr. Mike Dunphy>Well, it's like this. Earlier when I struck the bricks, I moved my hand at a speed that peaked out at about 50 feet per second. When I hit the bricks, I hit him in the weakest point in the middle. And that instant, when my hand touched those bricks, my hand exerted a force about the same as six hundred and seventy five pounds on top of those bricks.

<v David Heil>Mike, how do you get your hand deliver that kind of force? <v Dr. Mike Dunphy>Well, David, in a word, training. <v David Heil>[Karate noises] what's going on here. <v Dr. Mike Dunphy>Well, David, this is a group of advanced karate students practicing, [inaudible] Right. Have a seat in [inaudible] please. <v David Heil>You know, as I was watching them, it occurred to me that they basically were doing the same motion over and over again. Is that typical? <v Dr. Mike Dunphy>It is. In karate training. It's important to have repetition because the more you do the technique, the more often you do it, the stronger the hand becomes, the tissues become stronger and the bone included. <v Dr. Bruce Dan>They're doing more than just drinking their bones and their muscles. David, by doing repetitive motions over and over again, they're actually training their brain <v David Heil>Training their brain?

<v Dr. Bruce Dan>Sure. <v David Heil>More than just learning? <v Dr. Bruce Dan>These repetitive things, set down electrical impulses in the brain, sort of like memory pathways, they become more efficient. The better they do it, more power, more speed, because all of the body's movement is controlled by the brain. <v David Heil>So you are talking about something that's more than just memorization here? <v Dr. Bruce Dan>Oh, definitely. This is sort of like biofeedback because like a professional baseball player who takes batting practice, the more he practices those motions, the more his brain and the body get together, the better he hits the ball <v David Heil>And more accurate when it comes time to make that final motion. Is it possible to take somebody like myself who hasn't done karate before and trained me to do one of the key motions, like, I don't know, like breaking a board in half? <v Dr. Mike Dunphy>Well, sure. David, let's go over here. We have here a striking post that we're going to use as a tool to help learn the technique you need. But, David, this is something you only want to do under the supervision of a trained professional and it takes some time. <v David Heil>I think we've got a little bit of time here. <v Dr. Mike Dunphy>Well, great. <v David Heil>Dedicated to this. <v Dr. Mike Dunphy>Let's go for it. Let's put your feet here a little bit, We're going to do a technique called a Hammerfest, which is the same as a technique I used earlier to break the brick. So, you know, form your hand this way, David put your hand on top of the pad this way for me. And this hand is going to be out this way. Take this hand above your head like you're going through a curve ball. Is that hand drops to the pad, pull this one to your hip. <v David Heil>Like, just pull it back like this.

<v Dr. Mike Dunphy>That's right. <v David Heil>OK. <v Dr. Mike Dunphy>And breathe. <v David Heil>Breathe out? <v Dr. Mike Dunphy>Breathe out without when you strike. <v Dr. Mike Dunphy>That's great. OK, David, the training went really well, I think it's time for your first board break. <v David Heil>You think so? What is this, like a three quarter inch piece of kind of wood? <v Dr. Mike Dunphy>That's pine. <v David Heil>Pine. <v Dr. Bruce Dan>Don't worry David. I'm here for any first aid needs. <v David Heil>Thanks Bruce. That's very reassuring. <v David Heil>All right. OK. <v Dr. Mike Dunphy>Just like we did in practice. Now, Form your Hammerfest. <v David Heil>Pull this one back. <v Dr. Mike Dunphy>That's right. <v David Heil>OK. Do I say, anything I should've asked you that <v Dr. Mike Dunphy>I think if you have a good idea to really kiai scream as you hit the ball, real big kiai as best you can. OK. <v David Heil>Oh, what do you know. <v David Heil>It does tingle just a little bit just like you promised, sure enough, but it worked. It's amazing, Mike, thanks so much for the lesson. <v Dr. Mike Dunphy>My pleasure David.

<v Dr. Bruce Dan>Bruce, thanks for your help. <v Dr. Bruce Dan>Good enough, still got that elastic hand. <v David Heil>It's a stronger handshake, don't you think? Well, I made it through my first board, we'll have more, in just a minute. <v Peggy Knapp>Remember, our show depends on your questions, write to us at Newton's Apple 172 East 43rd Street Box 100 St. Paul, Minnesota, 555 101. You can also send us e-mail at the University of Minnesota, Newton's Dot Apple at Human Dot Edu or look us up on your favorite online service. <v Robin Leach>So join us now for another episode of Science of the Rich and Famous. Robin Leach, globetrotting journalist to the stars. <v Robin Leach>What? I'm so tired, I'm meeting myself coming and going, my jet lag must be worse than I thought.

<v Robin Leach>Mr. Leach, can I have your autograph? <v Robin Leach>I must be dreaming. I know I'll pinch myself awake. <v Robin Leach>Ouch,. <v Robin Leach>It's worse that I imagine you are real. Not just the result of an interruption in my natural circadian rhythms. <v Robin Leach>You're what? <v Robin Leach>Circadian rhythms, My internal biological clock. It's what causes us to wake up in the morning, eat at certain times. Become sleeply at night. It's so much a part of us. We don't notice it until something like jetting across several time zones throws it right out of whack. <v Robin Leach>Oh, jet lag. <v Robin Leach>Precisely. For example, I've just flown in from the land down under home to such rare wildlife as the duckbilled platypus, the cuddly koala and one of America's most sought after leading men, Mel Gibson. Now, according to this watch, it's three at Mel's exotic outback retreat. On the other hand, this elegant bauble a gift from [inaudible' indicates it's 1:00 pm in the Big Apple. So while you might be in the mood to grab a bite at the Russian tea room, my body's ready for bed. I'm still on Australian local time and 14 hours ahead, which is why I'd trade all my champagne wishes for some caviar dreams about now. <v Robin Leach>So all you need is sleep to cure jetlag.

<v Robin Leach>I wish it was so easy The sleep-wake cycle isn't the only rhythm to our biological clock. Our internal pacemaker actually comprises dozens of daily cycles, our blood pressure, our body temperature, as well as the levels of certain blood chemicals. In fact, almost all activities in our cells, glands and organs follow up nearly twenty four hour cycle. <v Robin Leach>Then dealing with jet lag isn't so simple. <v Robin Leach>Indeed not. See, not all these cycles will reset at the same rate. Some may take a day, while others take longer, depending on how many time zones you cross, which is why some travelers become fatigued or get the chills or sweats or just feel generally lousy. I try to counteract the jet lag by getting used to the new time zone before I get back. So I eat, sleep and wake up on the new schedule. Sounds complicated. There is one simple way to avoid jet lag altogether. Fly north or south. You won't cross any time zones. So you want to experience jet lag. Which is why my friend migrating birds don't suffer when they head south for the winter. Isn't it time for you to head out? Why don't you go and catch up with those swallows in Capistrano? I believe south is that way. <v Nancy Gibson>It's just a little test.

<v David Heil>I don't know Nancy, I mean, really Nancy wants me to wear this blindfold so that I can guess what the next guest is, you sure this is going to work? <v Nancy Gibson>I know it's going to work. Just hang tight here. All right. Bring in the animal. <v David Heil>What is this, a tree trunk? <v Nancy Gibson>Not even close. <v Nancy Gibson>How about a fire hose? <v Nancy Gibson>David. <v David Heil>This is hard. Maybe a mudflap. <v Nancy Gibson>Think animal. David. <v David Heil>Animal. <v Nancy Gibson>All right, David, have you figured <v David Heil>it out yet? Well, it's got to be huge. Whatever it is, I can only guess one animal. Yes, an elephant. <v David Heil>Yes. And a very big one at that. <v Nancy Gibson>Very big. <v David Heil>This is great right here in the warehouse. <v Nancy Gibson>I know. Can you imagine that? Let me introduce you. This is Luella and she's an African elephant. Let me give you a food pellet here. She was brought to us by Jodan Farms, in Franksfield, Wisconsin. And her handler is right behind, that is Bob Meyer. <v David Heil>Hi, Bob. <v David Heil>Glad to have him nearby. <v Nancy Gibson>Yes. Yes. <v David Heil>What a beautiful animal, ok. I've got this food pellet. Let's put the trunk to work. Look at this, It's almost like fingers on the end. <v Nancy Gibson>Remember the- <v David Heil>It is the only one I got, you have another one?

<v Nancy Gibson>Yes. <v Nancy Gibson>It's just a combination of your upper lip and the nose. And so they use that for a variety of reasons. They'll use it to suck up dust and water and spray their body and keep them warm. <v David Heil>Do they drink water through the nose? <v Nancy Gibson>No they just suck it up and then spray it out. <v Nancy Gibson>OK. But let me see if we- <v David Heil>Wow, look at that. <v Nancy Gibson>Oh, she likes [laughter] <v David Heil>Throw her right in there. Wow. Look at these ear. <v Nancy Gibson>Yes. Aren't hose ears something. <v David Heil>Now do just the big ears help them hear better? <v Nancy Gibson>They do have good hearing, but they will they'll use that as their cooling system and the blood will run from their body into their ears. They'll flap, their ears back and forth, cool off the blood and then shoot it back to the body. <v David Heil>So this is basically works like a radiator, just cools the blood down. <v Nancy Gibson>Right. <v David Heil>And the first thing I felt was that the leg. <v Nancy Gibson>That was the leg. <v David Heil>It was the leg. So it was like a tree trunk. <v Nancy Gibson>Now, David, she weighs seven thousand pounds, <v David Heil>Seven thousand pounds, all supported by four pillar like legs. <v Nancy Gibson>Yes. <v Nancy Gibson>You take a good look here. You can see here she's actually got digits at the end of her foot there.

<v David Heil>So those are actually like toenails. <v Nancy Gibson>Yes. <v David Heil>Individual toes. I had no idea <v Nancy Gibson>And back here where the heel would be is embedded in fat. And so it really gives them a broad, wide distribution. And I've seen African elephants in the wild. You don't you hardly see a footprint. <v David Heil>Now she weighs how much? <v Nancy Gibson>Seven thousand pounds, four feet. That's about the size of two family cars. <v David Heil>And then the recognizable tusks here. <v Nancy Gibson>Yes. Yes. The tusk, again, have a lot of purposes. They use it to plow up the ground if there is a drought and they need some water. They use it to tear up a tree bark to get to some of the trees. But this is the part that keeps them in constant danger. This is the ivy everyone looks for. It's all often replaced by synthetics, but people will poach the animals and just pull out the tusk and leave the whole body rotting in the wild. <v David Heil>Now, aren't elephants also up against a challenge just with reduced habitat? <v Nancy Gibson>Reduced habitat, but the real problem is human population explosion that pushed into these little pockets- <v David Heil>Too many people, not enough room for the elephants. <v Nancy Gibson>this is nature's masterpiece here.

<v David Heil>Probably takes a very big territory. <v Nancy Gibson>You got it right. <v David Heil>This is great, Nancy. Thanks so much. What a treat to have in the warehouse here. <v Nancy Gibson>Yeah, I think so, too. <v David Heil>Bob, thanks for your help. <v David Heil>It's all the time we have. We'll see you next time on Newton's Apple. <v Host>Newton's apple is made possible by a grant from 3M and its employees, creative people who put science to work for you, 3M innovation. <v Host>This is PBS.