D4K Top 10 Questions

After each D4K, we sort though all the calls and emails and pick out our top ten questions. Our guest experts then give us the answers. Did your question make the top ten?

When you're done with this year's, you can look back at questions and answers from previous seasons:

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Season 14: 2015–2016


Light bulb

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Electricity (November 2015)

Thanks to John Gardner, Professor of Mechanical and Biomedical Engineering, Boise State University; and Kip Sikes, Operation Analysis and Development Manager, Idaho Power for their answers

* What amount of electricity does the average person in the U.S. use in a week?  Show answer arrow down

We think of this in terms of horsepower. The average household uses 1.6 horses every second. It's like a constant horse riding around. That's how much electricity we are using all the time. (From Joel at Dalton Gardens Elementary School in Dalton Gardens)  Hide arrow right

* How do clouds get electricity?  Show answer arrow down

Lightning is a natural phenomenon that happens as the clouds move through the air. The atoms and molecules in the air and the water in the clouds have free electrons that get exchanged as the clouds move through the atmosphere. The electrons build up on the clouds and need a place to go. They'll usually go to the closest spot that's of a different charge level. That's usually why lightning will hit a tree. It happens in the atmosphere as a course of everyday events. (From Ryan at Dalton Gardens Elementary School in Dalton Gardens)  Hide arrow right

* How does electricity travel?  Show answer arrow down

There is more than one way electricity travels. Normally, we think of it traveling through a conductor, or a wire, where the electrons bounce and push each other through. Electricity can also be stored. A battery can be used for this. Overall, for electricity to flow, a circuit is needed that allows for a complete connection circle all the way around to the source. (From Megan at Valley View Elementary School in Boise)  Hide arrow right

* When was electricity discovered?  Show answer arrow down

We're not sure. A lot of understanding of electricity came about in Europe in the 1700s. Many of the scientists who made some of the discoveries have names that are associated with electric terminology. A volt came from the scientist Volta, and amps came from the scientist Ampere. It was over a period of hundreds of years that people studied or investigated electricity. In the 1800s, Thomas Edison created a grid that allowed the electricity to be sold to the people of New York City. (From Charlotte at Valley View Elementary School in Boise)  Hide arrow right

* How does electricity end up in everyone's home?  Show answer arrow down

Electricity is produced by a generator that has wires in it. It gets to your home through this series of wires, called a grid, that run between states or throughout your region. (From Tyler at Cynthia Mann Elementary School in Boise)  Hide arrow right

* How fast can electricity travel through water?  Show answer arrow down

If it's pure water, electricity won't travel through it at all. It can't, because the water acts like an insulator. Small impurities in the water, like tap or river water, conduct electricity. Impurities, like salt, are really good at conducting electricity. Impurities will allow more and more electricity to move through the water. When electricity flows, it flows at a speed close to the speed of light. This is very, very fast. (From Yoshi at Valley View Elementary School in Boise)  Hide arrow right

* Why is it that when you rub your feet across the carpet, you make electricity?  Show answer arrow down

It has to do with static electricity. When you rub your feet across the carpet, your shoes act as insulators. As electrons build up on your body, you get a charge of electrons that's different than somebody else. So, the more you rub, the more electrons transfer to you that you can't get off until you reach out and touch someone. Zap! That zap that you feel is a little mini lightning bolt and that's why it hurts. (From Owen at Dalton Gardens Elementary School in Dalton Gardens)  Hide arrow right

* How does tidal power work?  Show answer arrow down

Tidal power is similar to hydroelectric power that we are more familiar with in Idaho. The water is held up by dams and it gets higher and higher above the level of the river. We use gravity to move that water down to the level of the river. While it's on its way through, it spins a turbine that generates power. With tidal power, sometimes the tides will rise and fill the water behind a dam. They'll close the dam off, and then it looks like a hydro dam. Sometimes, if the tides are coming though a smaller area, like a river, they'll put propellers underwater, anchored to the floor of the river. The tide will move past the propellers and the flowing water moves the propellers, spinning a turbine that turns the generator. (From Kendall at Valley View Elementary School in Boise)  Hide arrow right

* What creates the electricity in solar panels and lightning?  Show answer arrow down

Solar panels are basically made of sand or silicon. As the sunlight hits them, the electrons get excited. Gates are used to let the electrons out in just one direction, which creates the current. The electrons then bounce out of the solar panels. Lightning is actually static electricity. As clouds rub against the atmosphere, charges build up that are different between the cloud and the earth. Once there's enough difference in the electrons, the positive and negative charges, the air is ionized. This creates that big zap that allows the electrons to go through the air and down to the ground to balance out the charges again. (From Ryan at Cynthia Mann Elementary School in Boise)  Hide arrow right

* What properties of metal and bone make them great conductors of electricity?  Show answer arrow down

Free electrons make a good conductor. A good conductor is something that is made of atoms that have a lot of electrons that can move from atom to atom without a lot of resistance, meaning they can move easily. If you have a piece of metal or bone, it doesn't mean electrons are moving through them constantly. It takes a difference in voltage to make them move. If you can push the electrons and they can move easily, that's what makes a good conductor. Something that's an insulator is where the electrons are bound very tightly together and don't move. Even if you push on the electrons, they are going to stay in place. (From Moses at Valley View Elementary School in Boise)  Hide arrow right

 

Diagram of a neuron

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Nervous System (October 2015)

Thanks to Dr. Mary River, Neurologist, St. Alphonsus Hospital, Boise for their answers

* Why are nerves so important to our body?  Show answer arrow down

Nerves are important to sense what's going on around you or within you. They tell your body where you are or what's around you. They tell your heart to speed up or slow down, your stomach when it's full, and they let your bladder know when you need to go to the bathroom. They are very important for every part of our functioning. (From Madeline at Anser Charter School in Boise)  Hide arrow right

* What are nerves made out of?  Show answer arrow down

Nerves are made out of axons like the wire that's in an electrical cord. There is an axon, or wire, that transmits the energy. The axon is covered with a coating called a myelin sheath, which protects it, and also keeps the electricity that is traveling along the axon from leaking out. (From Sophie at Anser Charter School in Boise)  Hide arrow right

* When you get older, will you get more nerves?  Show answer arrow down

You generally don't grow more nerves. You can heal an injured nerve if the injury is not too deep. If you injure the myelin sheath, or coating, of a nerve, you can regrow the coating. That's what happens when you bruise your funny bone. If you actually injure the axon of a nerve, most of the time, it doesn't re-grow. (From Olivia at Anser Charter School in Boise)  Hide arrow right

* What does the nervous system look like?  Show answer arrow down

If you look at the nervous system without any covering or with the naked eye, it would look whitish and a lot like firm jello. If you look at it microscopically, you would see bundles of nerves going up and bundles of nerves going down. It would look a lot like electrical cords bundled together. (From Henri at Cynthia Mann Elementary School in Boise)  Hide arrow right

* How fast does it take for your brain to recognize that it got hurt?  Show answer arrow down

The nerve fibers that sense discomfort or pain transmit messages very, very quickly in order to keep you from being hurt. If you touch a hot pan, those nerves transmit the message very quickly in order to get you to pull your hand away from the hot pan as soon as possible and avoid further injury. It would be in the range of 200 miles per hour. (From Harrison at Anser Charter School in Boise)  Hide arrow right

* Why do nerves respond so fast?  Show answer arrow down

Nerves respond quickly in order to keep you out of danger. If you step on a tack, then the nerve that you stimulated by doing that has to travel very quickly up to your brain to keep you from stepping on it further. Then a message travels back down allowing you to quickly step off the tack. This fast response helps keep you out of danger. (From Reid at Cynthia Mann Elementary School in Boise)  Hide arrow right

* Why does a nerve not regenerate when it gets harmed?  Show answer arrow down

Some nerves do regenerate. In the peripheral nervous system, the arms and legs, if a nerve is injured, it can sometimes re-grow if it hasn't been injured too severely. Most of the time, they don't. The number we are born with is the number that we get. You have to take good care of your nerves. (From Grant at Anser Charter School in Boise)  Hide arrow right

* Does the nervous system create fear?  Show answer arrow down

The nervous system doesn't create fear. It responds to fear. If you are walking in the woods and a bear shows up, your eyes see the bear. A message is then sent to the rest of the brain and the brain reacts, or responds, to that stimulation. (From Cooper at Anser Charter School in Boise)  Hide arrow right

* What makes people ticklish?  Show answer arrow down

There isn't a specific answer to that. The thought is that ticklish areas, like the bottom of your feet or under your arms, tend to be vulnerable. When they feel that something is going to happen, they withdraw for protection. (From Maddie at Trail Wind Elementary School in Boise)  Hide arrow right

* Why does it hurt so much when you hurt your elbow?  Show answer arrow down

It's not funny even though it is called the funny bone. The ulnar nerve is a nerve that goes to the pinky finger and half of the ring finger. It travels through a bony canal in the elbow. That groove of the canal in the elbow does not have a lot of protection. If you bang it, you actually bruise or shock the nerve. (From Wesley at Anser Charter School in Boise)  Hide arrow right

 

Skeleton of a dinosaur head

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Dinosaurs (October 2015)

Thanks to David Varricchio, Assistant Professor of Paleontology, Earth Science Department, Montana State University for their answers

* How did the dinosaurs go extinct?  Show answer arrow down

We know some things that occurred about the time dinosaurs went extinct. There were major changes in climate due to a lot of volcanic eruptions that altered the earth's atmosphere and changed temperatures. Also, there is really good evidence that an asteroid hit the earth's surface. These probably contributed to the extinction of dinosaurs. However, if you ask ten different paleontologists why, they will have ten different reasons. (From Cagney at Shadow Hills Elementary School in Boise)  Hide arrow right

* How did dinosaurs become fossils?  Show answer arrow down

Bones have a mineral crystal component to them. In some ways, they are like rocks to begin with. Other parts of our bones are filled with blood and nerve tissue. That material gets eaten by bacteria and rots away, leaving spaces. Through time, water under ground percolates through the rock and deposits other minerals and crystals that grow inside the spaces in that bone. (From Devon at Maranatha Christian School in Boise)  Hide arrow right

* How long did dinosaurs live?  Show answer arrow down

Dinosaur bones record growth lines, like the trees have growth rings. You can look at trees and count how old the tree is. In the same way, you can look at dinosaur bones and get an estimate of their age by looking at the growth lines. For the big dinosaurs, they lived 10, 20, maybe even 50 years. (From John at St. Mary's School in Moscow)  Hide arrow right

* Are dinosaurs related to birds or reptiles?  Show answer arrow down

You can think of dinosaurs and birds as really belonging to the reptile group. We typically think of them, as well as turtles, lizards, snakes, and crocodiles, as belonging to that group. We can say that birds are dinosaurs, and that dinosaurs and birds are reptiles. (From Ben at Clearwater Elementary School in Kooskia)  Hide arrow right

* How many species of dinosaurs are there?  Show answer arrow down

We can only guess at how many there were. When we look at the rocks that dinosaurs are found in, we probably only see a small sample of all the dinosaurs that once lived. So far, scientists have named about 600 species, but it's estimated that there may have been 2,000 or 3,000 dinosaurs through the whole Mesozoic Era. (From Dani at Lena Elementary School in Moscow)  Hide arrow right

* Why does a small mammal survive, but not the dinosaurs?  Show answer arrow down

Some people think that the small animal may have been able to find shelter, such as crawling into a burrow, when the asteroid hit. Other small animals, like turtles and frogs, may have swum down to the bottom of the pond and hidden in the mud for a few months. Big animals require lots of food and space, whereas smaller animals can get by on very little. (From Nicole at Pine Forrest Elementary School in North Carolina)  Hide arrow right

* In what era and what kind of dinosaurs lived in Idaho?  Show answer arrow down

We have rocks in eastern Idaho that are from 100 million years ago. That's the Cretaceous period. One dinosaur that has been found is the oryctodromeus. It was about the size of your typical dog, not a very big dinosaur. It ate plants. We've found teeth from some carnivorous dinosaurs, maybe raptors. There may be a big ductile type animal as well. Also, even though we have no bones, we do have eggs from what may be a big giant oviraptor. (From Parker at Highlands Elementary School in Boise)  Hide arrow right

* How many bones are there in a velociraptor?  Show answer arrow down

Velociraptors had a lot of bones, probably in the neighborhood of about 250. (From Jack at McDonald Elementary School in Moscow)  Hide arrow right

* Which dinosaurs had feathers?  Show answer arrow down

It's only been a few years since we've found feathers on dinosaurs. So far, the most common are the meat-eating dinosaurs, particularly the smaller ones. They are closely related to birds. Recently, feathers have been found from tyrannosaurus relatives. (From Ben at Horizon Elementary School in Boise)  Hide arrow right

* How many teeth did they have?  Show answer arrow down

They had about 60 teeth in their jaws at one time. For each tooth that you could see, they had a tooth that was ready to replace it. So in their smile, you would see about 60 teeth, although there were probably about 120 teeth total, half that you wouldn't have been able to see. (From Kendall at Camelot Elementary School in Lewiston)  Hide arrow right

 

Diagram of soundwaves emanating from a speaker

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Sound (October 2015)

Thanks to Steve Shropshire, Professor of Physics, Idaho State University; and Dr. Kathryn Levine, Assistant Professor of Physics, College of Idaho for their answers

* How are sounds made?  Show answer arrow down

When you make a sound, you are giving a little bit of energy to the air around you. A sound wave is a compression wave of all the molecules in the air that carry that energy from whatever made that sound to your ear. (From Jack at Shadow Hills Elementary School in Boise)  Hide arrow right

* How fast and how far does sound travel?  Show answer arrow down

At room temperature, sound travels at around 330 meters per second. It's quite fast. Sounds can travel great distances. A volcano near Indonesia exploded back in the 1800's. The sound was heard for hundreds of miles. That was through the air. Sound travels a little bit better through water. Whales can communicate with each other over hundreds of miles of ocean. (From Shelbe at North Star Charter School in Eagle)  Hide arrow right

* Why does sound travel in waves?  Show answer arrow down

A wave is a disturbance. If you push on something, like a table, you expect the whole table to move. With air or water, when you push on one part of it, it takes a while for that disturbance to move as it doesn't move all at once. It is more fluid. Like when you throw a rock in water, you can see the waves that the rock created. Air moves the same way. (From Noah at Dalton Elementary School in Dalton Gardens)  Hide arrow right

* How does sound travel through space?  Show answer arrow down

The same thing that happens on Earth happens in space. One molecule communicates the wave to the next. The difference is that in space the density of the air is a lot lower meaning the molecules are further apart. As long as there is gas or molecules in space, sound can travel. If there isn't anything, then sound can't travel. (From Alyssa at Whitman Elementary School in Lewiston)  Hide arrow right

* Why do a trumpet and a saxophone sound different, even when they are playing the same note?  Show answer arrow down

It has to do with how the sound resonates in the instruments. Longer and bigger instruments make lower sounds. Shorter and smaller instruments make higher pitched sounds. (From Braden at Lena Elementary School in Moscow)  Hide arrow right

* How does sound travel better through water?  Show answer arrow down

Water is denser than air. There is more stuff in water in a smaller space. The molecules are closer together. When molecules in water get a disturbance or energy from sound, they collide with other molecules more rapidly. Also, water is more elastic than air. All of this contributes to making the sound travel better and farther. (From Sarah in at Saint Mary's Elementary School in Moscow)  Hide arrow right

* How far can a fire alarm sound travel?  Show answer arrow down

It depends on the fire alarm. The amount of energy that is produced, or the volume of the alarm, dictates how far the sound will travel. The louder the alarm, the further it's sound will travel. Large apartment buildings may have very loud alarms and they could be heard from further away. Smaller alarms, like those in the schools, may not be as loud and nearby houses may not hear them. (From Shaun who is homeschooled in Illinois)  Hide arrow right

* How many animals use sound to navigate their way around the world?  Show answer arrow down

Bats use sound to navigate and to hunt. They actually listen very closely to the sound that bounces off of insects and objects around them. A lot of fish and ocean creatures also use sound to navigate and hunt. Even some birds use sound. (From Cameron at Dalton Elementary School in Dalton Gardens)  Hide arrow right

* Why can't you see sound waves?  Show answer arrow down

A sound wave is a little tiny molecule that you can't see. You can't see the air even though there is stuff in the air. The small things in the air transmit the sound. They are all so tiny that we can't see them. (From Matilda at Dalton Elementary School in Dalton Gardens)  Hide arrow right

* How fast do you have to go to break the sound barrier?  Show answer arrow down

The speed of sound is 330 meters per second at room temperature. So that's about how fast you would have to go. (From Alex at Paramount Elementary School)  Hide arrow right

 

A swirl of galaxies

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Galaxies (September 2015)

Thanks to Dr. Amber Straughn, Research Astrophysicist at the Goddard Space Flight Center, NASA and Deputy Project Scientist for James Webb Space Telescope Education and Public Outreach for their answers

* Can other galaxies support human life?  Show answer arrow down

Nobody knows for sure. There are about 100 billion stars in our Milky Way, and about 100 billion other galaxies. Many of those stars have planets, but it takes a lot of very special conditions for life to be able to develop on a planet like Earth. This is a huge question, and because there are so many stars and planets, I think there probably is life out there. (From Alex at Paramount Elementary School in Meridian)  Hide arrow right

* If you could go into space forever, what would you find out there?  Show answer arrow down

We don't know how big the universe is. So, if you were to start traveling, nobody knows how far you could go. Humans have only been as far as the moon, and that was a long time ago. NASA is trying to figure out how to get humans beyond the moon, like an asteroid or even Mars. Kids in middle school are at a perfect age to start thinking about becoming an astronaut. One of you could be the first person to step foot on Mars! (From Jack at McDonnell Elementary School in Moscow)  Hide arrow right

* How many stars can you see at night?  Show answer arrow down

It depends on where you live. If you live in a city, the lights from the city can drown out a lot of the stars you would have been able to see. If you live in the country, there aren't as many city lights, and you can see many, many stars. (From Courtney at Saint Mary's Elementary School in Moscow)  Hide arrow right

* How many galaxies are out there?  Show answer arrow down

Astronomers don't know exactly how many galaxies there are. That's why we need kids like you to study astronomy, work for NASA and help figure out these questions. Astronomers do think there are about 100 billion other galaxies besides our Milky Way. (From Caleb who is homeschooled in Illinois)  Hide arrow right

* How do scientists take pictures of our galaxy?  Show answer arrow down

We actually can't do that. It would take way too long to get outside of the Milky Way to be able to take a picture of it. We've had to learn about it through other means, like studying the stars and how they are moving. That helps us learn about our own Milky Way. (From Iris at Cynthia Mann Elementary School in Boise)  Hide arrow right

* What would happen if two galaxies collided?  Show answer arrow down

Two galaxies colliding is a very common occurrence in the universe. You get a big galactic fireworks show when this occurs. One thing that occurs is that the galaxies lose their shape. If galaxies started out as disks or spiral galaxies, once they merge, they would typically become a ball shaped galaxy. Lots of crazy things happen when galaxies collide. (From Ethan at Cynthia Mann Elementary School in Boise)  Hide arrow right

* What is past our galaxies?  Show answer arrow down

Galaxies, in the past, were called Island Universes. They are mostly sitting out there in space. Bigger galaxies, like our Milky Way, have smaller galaxies orbiting around them. Just beyond our galaxy is mostly open space. Then much further away, there are bigger galaxies like ours. (From Sophie at Riverstone International School in Boise)  Hide arrow right

* How are galaxies made?  Show answer arrow down

A galaxy is a collection of stars. All the stars are made individually, and they are born out of clouds of gas and dust. The whole galaxy itself is born at different times within the universe. (From Ross at Cynthia Mann Elementary School in Boise)  Hide arrow right

* How many miles away is the farthest known galaxy?  Show answer arrow down

We measure very distant galaxies in terms of light years, or how far light can travel in a year. The most distant galaxies that we've discovered are over 13 billion light years away. NASA is building new telescopes, like the James Webb Space Telescope, to help us see early galaxies that we haven't been able to view yet. (From Michael at McDonald Elementary School in Moscow)  Hide arrow right

* How many planets are in our galaxy?  Show answer arrow down

We don't know. Great NASA missions have discovered many, many planets in our own galaxy. We now think that there are more planets than stars in the universe. How many? We don't know, but we know there are a lot! (From Annika at Whitman Elementary School in Lewiston)  Hide arrow right

 

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