NASA Proves It! A Feather and a Steel Ball Fall Together — Why Do They Hit the Ground at the Same Time? Galileo’s Astonishing Law of Falling

I am Ken Kuwako, your science trainer. Every day is an experiment.

Have you ever fumbled your smartphone and watched it slip through your fingers? In that split second of panic, a grand set of rules governing the entire universe is actually at work. Isn’t that exciting? We’ve all heard the legend of Isaac Newton discovering gravity after watching an apple fall from a tree. Even today, the simple, everyday phenomenon of things falling is packed with enough drama to leave us in awe.Time for a quick quiz: If you drop a sheet of paper and a heavy rock at the same time, which one hits the ground first? “The heavy rock, obviously!” If that was your first thought, welcome to the fascinating world of physics!Actually, that bit of common sense can be flipped on its head like magic under the right conditions. Today, I want to take you on a journey into the hidden mysteries of science: the world of falling motion.

Question Everything! Galileo and the Mystery of Falling

Over 400 years ago, the great scientist Galileo Galilei had the same question you just answered. For nearly 2,000 years, people had blindly followed Aristotle’s teaching that heavier objects fall faster.But Galileo thought for himself. He hypothesized: “If there were no air to get in the way, every object should fall at exactly the same speed, regardless of its weight.” To prove this intuition, legend has it he dropped two spheres of different masses from the Leaning Tower of Pisa to shock the onlookers. (While some say this was actually a thought experiment, the excitement of the idea remains the same!)”Wait a second,” you might say. “If I drop a feather and a ball right now, the ball definitely hits first!”You’re absolutely right. That is because of air resistance—an invisible brake. A light feather gets tossed around by air molecules, while a heavy ball cuts right through them. But what happens if we take the air away?

NASA Proves It! In a Vacuum, Feathers and Bowling Balls Fall Together

The BBC recently teamed up with NASA to perform a dream experiment in a massive facility. The stage was the world’s largest vacuum chamber—a room where every single molecule of air is sucked out to create a void just like the surface of the Moon.First, they dropped a bowling ball and some feathers with air in the room. Naturally, the ball crashed down while the feathers drifted slowly. But after running the pumps for hours to create a giant vacuum, they dropped them again, and then…

Source: BBC TWO

https://youtu.be/E43-CfukEgs?si=FcopVUJoByNEwj0QThe sight is unbelievable. The light, fluffy feathers and the heavy bowling ball fall in perfect synchronization, hitting the floor at the exact same moment. It is a stunning moment where the truth written in physics textbooks—that all objects accelerate equally—manifests right before your eyes. Now, let’s use the magic language of mathematics to decode the secrets of this beautiful falling motion.

Adventure with Math! Decoding the 2 Main Patterns of Falling

Falling happens because Earth’s gravity is constantly pulling on an object. As it falls, its speed increases at a steady rate. This rate of speeding up is called gravitational acceleration, represented by the symbol $g$. On Earth, it’s approximately $9.8 \text{ m/s}^2$. This means that for every second that passes, the object gets $9.8 \text{ m/s}$ faster. If you know this rule, you can predict the future speed and distance of any falling object just by calculating!

Pattern 1: Free Fall (Gently Letting Go)

This is the simplest form of falling: just opening your hand and letting an object drop. The key is that the initial velocity ($v_0$) is 0. For example, if you drop a small ball from a tall tree and it hits the ground in exactly 2.0 seconds, how high is that tree?

We use the formula for distance. By plugging in $t=2.0$ seconds and $g=9.8 \text{ m/s}^2$, we get:

The tree is about 20 meters tall! That’s roughly the height of a 5 or 6-story building.

Pattern 2: Vertical Throw-Down (Throwing with Force)

Next is when you throw something downward with a bit of a “oomph.” If you throw a ball downward with an initial speed of $5.0 \text{ m/s}$, what will its speed and distance be after 2.0 seconds?

This time, the initial speed of $5.0 \text{ m/s}$ gives it a head start. First, let’s calculate the final speed after 2.0 seconds.If you convert this to km/h, it’s about 90 km/h—as fast as a car on a highway! Now, let’s look at how far it traveled in those 2.0 seconds.It traveled 30 meters, which is 10 meters further than if you had just dropped it. Using math like this allows us to visualize these physical phenomena with incredible precision.By the way, did you know that NASA experiment took 3 hours just to pump the air out of the chamber? I have so much respect for that kind of dedication to scientific truth. You should also check out the footage from the Apollo mission where they actually performed the “hammer and feather” experiment on the Moon!https://phys-edu.net/wp/?p=33844

Inquiries and Requests

Let’s make the wonders of science a part of your daily life! I share fun experiments you can do at home and tips that make every day more interesting through the lens of science.Learn more about me, Ken Kuwako, here.For inquiries regarding writing, lectures, science workshops, or TV consultation, click here.Check out my latest updates on X (formerly Twitter)!

Explore more experiments on my Science Channel!

２月のイチオシ実験！梱包材で遊ぼう！

• 静電気の時期になってきました。子供と一緒に梱包材で盛り上がろう！→ やめられなくなる！静電気実験２０

体中に梱包材をはりつけてみよう！

テレビ番組等・科学監修等のお知らせ

• 「月曜から夜更かし」（日本テレビ）にて科学監修・出演しました。

書籍のお知らせ

• 1/27 『見えない力と遊ぼう！電気・磁石・熱の実験』（工学社）を執筆しました。
• サクセス15 ２月号にて「浸透圧」に関する科学記事を執筆しました。
• 『大人のための高校物理復習帳』（講談社）…一般向けに日常の物理について公式を元に紐解きました。特設サイトでは実験を多数紹介しています。※増刷がかかり６刷となりました（2026/02/01）
• 『きめる!共通テスト 物理基礎 改訂版』（学研）…　高校物理の参考書です。イラストを多くしてイメージが持てるように描きました。授業についていけない、物理が苦手、そんな生徒におすすめです。特設サイトはこちら。

講師等・ショー・その他お知らせ

• 2/20（金）「生徒の進学希望実現支援事業」研究授業＠福井県立若狭高等学校　講師
• 3/20（金）　日本理科教育学会オンライン全国大会2026「慣性の法則の概念形成を目指した探究的な学びの実践」について発表します。B会場 第３セッション： 学習指導・教材（中学校）③　11:20-12:20
• 7/18（土）　教員向け実験講習会「ナリカカサイエンスアカデミー」の講師をします。お会いしましょう。
• 10/10（土）　サイエンスショー予定
• 各種SNS　X(Twitter)／instagram／Facebook／BlueSky／Threads

Explore

• 楽しい実験…お子さんと一緒に夢中になれるイチオシの科学実験を多数紹介しています。また、高校物理の理解を深めるための動画教材も用意しました。
• 理科の教材… 理科教師をバックアップ！授業の質を高め、準備を効率化するための選りすぐりの教材を紹介しています。
• Youtube…科学実験等の動画を配信しています。
• 科学ラジオ …科学トピックをほぼ毎日配信中！AI技術を駆使して作成した「耳で楽しむ科学」をお届けします。
• 講演 …全国各地で実験講習会・サイエンスショー等を行っています。
• About …「科学のネタ帳」のコンセプトや、運営者である桑子研のプロフィール・想いをまとめています。
• お問い合わせ …実験教室のご依頼、執筆・講演の相談、科学監修等はこちらのフォームからお寄せください。