# What is physics?

An episode of [Science for Kids / Science's Not Boring: The Kids Science Podcast](https://invisiblenetwork.ai/podcast/1896928296), 24 Jun 2026, 12 min.

Audio: https://www.buzzsprout.com/2624612/episodes/19382563-what-is-physics.mp3

Did you know that right now, even while you are sitting perfectly still, you are zooming through space at 67,000 miles per hour?! How is that even possible? Welcome to the incredible world of physics! In this episode of Science is Not Boring, Mira and Finn uncover the giant, invisible rulebook that controls how everything in the entire universe moves. Travel back to the year 1665 to meet a young scientist named Isaac Newton, who watched an apple fall and asked one brilliant question that changed history forever! Discover the amazing laws of motion, from the "laziness" of inertia that keeps the Voyager 1 spacecraft coasting through deep space forever, to the massive power of the Saturn V rocket blasting humans to the moon. We will even explore why the moon doesn't crash into your backyard, and what happens to astronauts when they float in zero gravity (hint: they actually grow taller!). Get ready to learn how a simple kick of a ball connects to the massive forces that run the galaxies. Physics is all around us, and it feels just like magic! Join us to explore the invisible rules of the universe!

## Transcript

[0:46] SPEAKER_00: Welcome to Science is Not Boring by Kidopoly.com.
[0:50] SPEAKER_00: I'm Mira.
[0:51] SPEAKER_00: And I'm Finn.
[0:53] SPEAKER_00: Before we start, a big hello to Kristen and Rai, who asked us all about the laws of physics.
[0:59] SPEAKER_00: This one is for you.
[1:01] SPEAKER_01: Yeah, thanks for the awesome idea, Kristen and Rai.
[1:04] SPEAKER_01: We're ready to get moving.
[1:05] SPEAKER_00: Okay Finn, did you know that right now, even though you are sitting completely still, you are actually zooming through space at 67,000 miles per hour.
[1:17] SPEAKER_01: Wait, what?
[1:19] SPEAKER_01: 67,000 miles per hour?
[1:22] SPEAKER_01: I'm not even wearing my seatbelt.
[1:24] SPEAKER_00: How is that possible?
[1:26] SPEAKER_00: Because you are on planet Earth, and Earth is racing around the Sun at incredible speed.
[1:32] SPEAKER_00: We're travelling about 18.5 miles every single second.
[1:37] SPEAKER_01: 18.5 miles in one second?
[1:40] SPEAKER_01: One, Mississippi.
[1:42] SPEAKER_01: Boom! We just travelled almost 20 miles.
[1:46] SPEAKER_00: Exactly.
[1:47] SPEAKER_00: And you don't feel it because of the invisible rules that control every push, pull, float, and fall in the universe.
[1:55] SPEAKER_00: Today we're talking about the incredible laws of physics.
[1:59] SPEAKER_01: So, physics is like the giant invisible rulebook for how everything moves.
[2:04] SPEAKER_00: You got it! From throwing a baseball to rockets launching into deep space.
[2:10] SPEAKER_00: Everything has to follow these rules.
[2:12] SPEAKER_00: Let's uncover the secrets of the universe.
[2:15] SPEAKER_00: If you go outside on a clear summer night and look up at the stars, it feels so peaceful.
[2:21] SPEAKER_00: But up there, planets, moons, and asteroids are constantly spinning and flying in perfect balance.
[2:29] SPEAKER_01: Yeah, why doesn't the moon just fall down and crash into my backyard?
[2:33] SPEAKER_00: People wondered that for thousands of years.
[2:36] SPEAKER_00: To answer it, we have to travel back to the year 1665.
[2:41] SPEAKER_00: A 22-year-old scientist named Isaac Newton was trying to study at Cambridge University.
[2:47] SPEAKER_00: Cambridge is in England, right?
[2:49] SPEAKER_00: What was he studying?
[2:50] SPEAKER_00: He was studying math and science, but then something terrifying happened.
[2:55] SPEAKER_00: The Great Plague broke out.
[2:57] SPEAKER_00: It was a disease spread by tiny fleas, and it forced the whole university to close down.
[3:03] SPEAKER_01: Ew, fleas spreading sickness.
[3:06] SPEAKER_01: That is definitely gross.
[3:08] SPEAKER_01: So what did Isaac do?
[3:10] SPEAKER_01: Did he just play video games inside?
[3:13] SPEAKER_00: No video games back then.
[3:15] SPEAKER_00: He packed his bags and went back to his family farm, a place called Woolsthorpe Manor.
[3:21] SPEAKER_00: And one day, he was sitting in the orchard, looking at a specific type of apple tree called a flower of Kent.
[3:28] SPEAKER_01: Oh, I know this one.
[3:29] SPEAKER_01: An apple fell and bonked him right on the head, and he yelled, Gravity!
[3:34] SPEAKER_00: That's the famous myth! But historians think he just watched the apple fall from a distance.
[3:40] SPEAKER_00: The real magic wasn't the bonk on the head.
[3:42] SPEAKER_00: It was the question he asked himself.
[3:45] SPEAKER_00: What was the question?
[3:46] SPEAKER_00: He asked, Why does the apple always fall straight down to the centre of the earth?
[3:51] SPEAKER_00: Why doesn't it go sideways or up?
[3:54] SPEAKER_00: He realised there had to be an invisible pulling force.
[3:57] SPEAKER_00: He called it gravity.
[3:59] SPEAKER_00: That apple incident led Newton to figure out the three laws of motion.
[4:03] SPEAKER_00: These are the absolute rules for how stuff moves.
[4:07] SPEAKER_00: Rule number one is all about laziness.
[4:11] SPEAKER_01: Laziness?
[4:12] SPEAKER_01: Like me on a Sunday morning.
[4:14] SPEAKER_00: Exactly.
[4:15] SPEAKER_00: It's called inertia.
[4:17] SPEAKER_00: It means objects want to keep doing whatever they're already doing.
[4:21] SPEAKER_00: A ball on the ground will stay still forever until you kick it.
[4:25] SPEAKER_00: But here's the wild part.
[4:27] SPEAKER_00: If you kick a ball in deep space, it will keep moving forever.
[4:32] SPEAKER_01: Wait, forever?
[4:33] SPEAKER_00: It would never stop.
[4:35] SPEAKER_00: Never! Unless something hits it.
[4:38] SPEAKER_00: Think about the Voyager 1 spacecraft.
[4:40] SPEAKER_00: We launched it in 1977.
[4:43] SPEAKER_00: Right now, it's over 15 billion miles away from Earth, coasting at 38,000 miles per hour.
[4:51] SPEAKER_00: 15 billion miles?
[4:53] SPEAKER_00: And it doesn't run out of gas?
[4:55] SPEAKER_00: Nope.
[4:56] SPEAKER_00: Because space is mostly empty, there's no air to slow it down.
[5:00] SPEAKER_00: It's just riding on inertia.
[5:02] SPEAKER_00: Now, Newton's second rule is about mass and force.
[5:06] SPEAKER_00: It basically says heavy things are harder to move than light things.
[5:10] SPEAKER_01: Well, yeah, obviously.
[5:12] SPEAKER_01: I can throw a tennis ball, but I can't throw a 500-pound gorilla.
[5:16] SPEAKER_00: Right.
[5:17] SPEAKER_00: But if you wanted to make that 500-pound gorilla accelerate on a skateboard, you would need a massive push.
[5:24] SPEAKER_00: Scientists write this as F equals MA, or force equals mass times acceleration.
[5:31] SPEAKER_00: So what's the third rule?
[5:32] SPEAKER_00: Does the gorilla push back?
[5:34] SPEAKER_00: He sure does.
[5:35] SPEAKER_00: The third law says for every action, there is an equal and opposite reaction.
[5:41] SPEAKER_00: If you push hard against a wall, the wall is actually pushing back on you with the exact same amount of force.
[5:48] SPEAKER_00: Wait, if the wall pushes back, why doesn't it knock me over?
[5:52] SPEAKER_00: Because you have friction between your shoes and the ground keeping you steady.
[5:56] SPEAKER_00: But this third law is exactly how rockets work.
[5:59] SPEAKER_00: Think about a rocket launching into space.
[6:02] SPEAKER_00: Oh, it blasts fire down, so the rocket goes up.
[6:06] SPEAKER_00: Yes! The Saturn V rocket, which took humans to the moon, created 7.6 million pounds of thrust.
[6:14] SPEAKER_00: It blasted 15 tons of fuel out of its engines every single second.
[6:19] SPEAKER_00: That downward blast pushed the giant rocket up into the sky.
[6:25] SPEAKER_01: 15 tons of fuel every second.
[6:28] SPEAKER_01: That's like exploding 10 cars out of the engine every time the clock ticks.
[6:33] SPEAKER_00: That is a perfect way to picture it.
[6:36] SPEAKER_00: Now, let's connect it all back to gravity.
[6:40] SPEAKER_00: Newton realised that gravity doesn't just pull apples, it stretches all the way into space.
[6:46] SPEAKER_00: It's the invisible string keeping the moon from flying away.
[6:50] SPEAKER_01: But if gravity is pulling the moon, why doesn't it fall and hit us?
[6:54] SPEAKER_00: Because the moon is moving sideways extremely fast.
[6:59] SPEAKER_00: About 2,288 miles per hour.
[7:03] SPEAKER_00: It wants to fly in a straight line because of inertia, but Earth's gravity constantly pulls it inward.
[7:09] SPEAKER_00: So it falls around the Earth in a circle.
[7:12] SPEAKER_01: Whoa! So it's always falling, but it's moving so fast sideways that it keeps missing the ground.
[7:19] SPEAKER_00: You just perfectly described an orbit.
[7:22] SPEAKER_00: That's exactly what the International Space Station does too.
[7:26] SPEAKER_00: It travels at 17,500 miles per hour just to keep missing the Earth.
[7:32] SPEAKER_01: So every time I ride my bike, or drop a pencil, or throw a frisbee, I'm using these same physics laws that run the galaxies.
[7:41] SPEAKER_00: Absolutely! Engineers use these exact rules to build massive skyscrapers that don't fall over, and roller coasters that keep you locked in your seat even when you go upside down through a loop.
[7:54] SPEAKER_01: Does gravity change depending on where you are?
[7:57] SPEAKER_01: Like, what if I lived on another planet?
[8:00] SPEAKER_00: It completely changes.
[8:02] SPEAKER_00: Gravity depends on how much mass an object has.
[8:06] SPEAKER_00: Jupiter is so massive that its gravity is 2.5 times stronger than Earth's.
[8:13] SPEAKER_00: If you weigh 100 pounds here, you would feel like you weigh 253 pounds on Jupiter.
[8:20] SPEAKER_00: You could barely lift your own arms.
[8:23] SPEAKER_01: 253 pounds?
[8:25] SPEAKER_01: I wouldn't even be able to get out of bed.
[8:28] SPEAKER_01: What happens if there's almost no gravity?
[8:30] SPEAKER_00: Well, when astronauts go to space, they experience microgravity.
[8:36] SPEAKER_00: And something really weird happens to their bodies.
[8:39] SPEAKER_00: Without gravity pushing down on their heads all day, the spongy disks between their spine bones expand with fluid.
[8:47] SPEAKER_01: Ew, my spine would fill with fluid and stretch out like a slinky.
[8:52] SPEAKER_00: It's totally safe, but yes, astronauts can actually grow up to two inches taller while they are living in space.
[9:00] SPEAKER_00: When they return to Earth, gravity squishes them back to their normal height.
[9:05] SPEAKER_01: That is the weirdest superpower ever.
[9:08] SPEAKER_01: Becoming two inches taller just by floating.
[9:10] SPEAKER_01: Alright, Finn, time for the quiz.
[9:12] SPEAKER_01: Are you ready?
[9:13] SPEAKER_01: Okay, I've got my brain in gear.
[9:16] SPEAKER_01: Bring on the physics questions.
[9:18] SPEAKER_00: Okay, first question.
[9:20] SPEAKER_00: How fast is planet Earth zooming through space around the Sun?
[9:27] SPEAKER_00: Next one, this is tricky.
[9:29] SPEAKER_00: What was the name of the scientist who figured out the laws of motion in 1665?
[9:39] SPEAKER_00: Question three.
[9:40] SPEAKER_00: Which spacecraft is coasting 15 billion miles away from Earth right now at 38,000 miles per hour?
[9:52] SPEAKER_00: Alright, here's number four.
[9:54] SPEAKER_00: How many pounds of thrust did the Saturn V rocket create to launch into space?
[10:03] SPEAKER_00: Last question.
[10:04] SPEAKER_00: How much taller can astronauts grow when they live in space?
[10:11] SPEAKER_00: Great job, let's go through the answers.
[10:14] SPEAKER_00: The answer to question one is Earth is travelling at 67,000 miles per hour.
[10:22] SPEAKER_00: For question two, it was Isaac Newton.
[10:26] SPEAKER_00: Number three, the answer is Voyager 1.
[10:30] SPEAKER_00: Question 4.
[10:31] SPEAKER_00: The Saturn V created 7.6 million pounds of thrust.
[10:37] SPEAKER_00: And the final answer is astronauts can grow up to two inches taller.
[10:42] SPEAKER_01: Wow, I am never going to look at throwing a ball the same way again.
[10:47] SPEAKER_01: Knowing that it's all part of the same rules that keep the moon flying is incredible.
[10:53] SPEAKER_00: I know! Physics makes everything feel like magic, but it's totally real! You're interacting with it every single second of the day.
[11:02] SPEAKER_01: If you loved learning about gravity, rockets, and floating astronauts today, please leave us a five-star review.
[11:09] SPEAKER_01: Just scroll down and tap the stars.
[11:11] SPEAKER_00: And don't forget to check out our site, kidopoly.com.
[11:15] SPEAKER_00: We've got tons of fun learning games and activities there.
[11:18] SPEAKER_01: Want your name on the show, like Kristen and Rye?
[11:22] SPEAKER_01: Send us an email at hello at kidopoly.com.
[11:25] SPEAKER_00: Thanks for exploring the amazing rules of the universe with us.
[11:29] SPEAKER_00: See you next time on Science is Not Boring.
[11:33] SPEAKER_00: Bye everyone.
[11:34] SPEAKER_01: Watch out for falling apples.

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