物質を理解するために欠かせない「体積」と「質量」について学んでいこう。普段何気なく使っている「重さ」と「質量」は実は違うもので、正確な測り方にもコツがあるんだ。実験でよく使うメスシリンダーや上皿てんびんの使い方をマスターして、テストでも実験でも自信を持てるようになろう！
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Updated Apr 1, 2026
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体積と質量の基本を理解する
1 / 6
体積と質量の基本
君たちが毎日使っているものにも、必ず体積と質量がある。体積は物質が占める空間の大きさで、単位は**cm³（立方センチメートル）やmL（ミリリットル）**を使うよ。
質量は場所が変わっても変化しない、物質そのものの量のこと。単位は**g（グラム）やkg（キログラム）**で表す。ここで注意したいのが、普段使う「重さ」とは違うということ！
重さは月に行くと軽くなるけど、質量はどこでも同じなんだ。実験ではメスシリンダーで体積を、上皿てんびんで質量を正確に測ることができる。
覚えておこう！ 1cm³ = 1 mL という関係は計算問題でよく使うよ。
液体の体積測定とメニスカス
液体の体積を測るときはメスシリンダーを使う。まず水平な場所に置いて、測りたい液体を注いだら、目の高さを液面に合わせて水平に目盛りを読むんだ。
ここで重要なのがメニスカスという現象。液体の表面は、ふちが少し盛り上がって中央がへこんだカーブになる。目盛りは、このへこんだ部分の底を読むのが正しい方法だよ。
見上げたり見下ろしたりすると正確な値が読めないから、必ず目の高さを合わせること。メスシリンダーの最小目盛りも確認して、その1/10まで目分量で読み取ろう。
実験のコツ！ メニスカスの底を読むのがポイント。目の高さを液面に合わせるのを忘れずに！
固体の体積測定法
固体の体積は形によって測り方が変わる。直方体のような形が整っているものは、定規で長さを測って計算で求められる。公式は「体積 = たて × 横 × 高さ」だ。
石ころのような不規則な形の固体は、メスシリンダーと水を使った方法で測る。まず固体が完全に沈む量の水を入れて体積を読み（V₁）、次に固体を静かに入れた後の体積を読む（V₂）。
固体の体積 = V₂ - V₁ という計算で求められる。水がはねないように静かに入れるのがポイントだよ。この方法なら、どんな複雑な形でも正確に測定できる。
計算のコツ！ 増えた分の体積がそのまま固体の体積になる。V₂からV₁を引くだけ！
上皿てんびんの正しい使い方
上皿てんびんで質量を測るときは、正しい手順が大切だ。まず水平な台に置いて、左右の皿に何も乗せずに針が中央で同じくらい振れるか確認する。
測りたいものを左の皿に乗せて、右の皿にはピンセットを使って分銅を乗せていく。質量の大きい分銅から順に乗せて、針が中央に来るように調整しよう。
絶対に分銅を手でさわってはいけない！ 汚れたりさびたりして質量が変わってしまうからだ。薬品を測るときも、直接皿に乗せず薬包紙を使うこと。
皿に乗っている分銅の質量の合計が、測りたいものの質量になる。左右の皿に同じ大きさの薬包紙を乗せてから測り始めるのも忘れずに。
注意ポイント！ 分銅は必ずピンセットで扱う。手の汚れで測定値が変わっちゃうよ！
計算問題と実践例
実際の計算問題を解いてみよう。石の体積を求める問題では、メスシリンダーに50.0 mLの水を入れ、石を沈めたら65.0 mLになったとする。
石の体積は 65.0 mL - 50.0 mL = 15.0 mL となる。1 mL = 1 cm³ という関係を使って、答えは15.0 cm³だ。
食塩水の質量を求める問題では、空のビーカーが52.5g、食塩水を入れた全体が113.8gの場合を考える。食塩水だけの質量は 113.8g - 52.5g = 61.3g となる。
このように、全体から容器の質量を引けば中身の質量がわかる。計算の考え方を理解すれば、どんな問題でも解けるようになるよ。
計算のコツ！ 「増えた分」や「差し引いた分」を考えれば、複雑そうな問題も簡単に解ける！
質量と重さの決定的な違い
テストでよく出る質量と重さの違いをしっかり覚えよう。質量は物質そのものの量で、どこにいても変わらない。重さは重力の大きさで、場所によって変化する。
測る器具も違っていて、質量は上皿てんびん、重さはばねはかりを使う。単位も質量はg・kg、重さはN（ニュートン）と区別されている。
月に行くと体重は約1/6になるけど、質量は地球にいるときと全く同じ。この例を覚えておけば、テストで間違えることはないよ。
実験では正確な測定が重要だから、メスシリンダーの読み方や上皿てんびんの使い方をしっかりマスターしよう。練習すれば必ずできるようになる！
テスト対策！ 「月では体重が軽くなるけど質量は同じ」という例で覚えれば完璧！
We thought you’d never ask...
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Our AI Companion is a student-focused AI tool that offers more than just answers. Built on millions of Knowunity resources, it provides relevant information, personalised study plans, quizzes, and content directly in the chat, adapting to your individual learning journey.
Where can I download the Knowunity app?
You can download the app from Google Play Store and Apple App Store.
Is Knowunity really free of charge?
That's right! Enjoy free access to study content, connect with fellow students, and get instant help – all at your fingertips.
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4.7/5
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The app is very easy to use and well designed. I have found everything I was looking for so far and have been able to learn a lot from the presentations! I will definitely use the app for a class assignment! And of course it also helps a lot as an inspiration.
Stefan S
iOS user
This app is really great. There are so many study notes and help [...]. My problem subject is French, for example, and the app has so many options for help. Thanks to this app, I have improved my French. I would recommend it to anyone.
Samantha Klich
Android user
Wow, I am really amazed. I just tried the app because I've seen it advertised many times and was absolutely stunned. This app is THE HELP you want for school and above all, it offers so many things, such as workouts and fact sheets, which have been VERY helpful to me personally.
Anna
iOS user
Best app on earth! no words because it’s too good
Thomas R
iOS user
Just amazing. Let's me revise 10x better, this app is a quick 10/10. I highly recommend it to anyone. I can watch and search for notes. I can save them in the subject folder. I can revise it any time when I come back. If you haven't tried this app, you're really missing out.
Basil
Android user
This app has made me feel so much more confident in my exam prep, not only through boosting my own self confidence through the features that allow you to connect with others and feel less alone, but also through the way the app itself is centred around making you feel better. It is easy to navigate, fun to use, and helpful to anyone struggling in absolutely any way.
David K
iOS user
The app's just great! All I have to do is enter the topic in the search bar and I get the response real fast. I don't have to watch 10 YouTube videos to understand something, so I'm saving my time. Highly recommended!
Sudenaz Ocak
Android user
In school I was really bad at maths but thanks to the app, I am doing better now. I am so grateful that you made the app.
Greenlight Bonnie
Android user
very reliable app to help and grow your ideas of Maths, English and other related topics in your works. please use this app if your struggling in areas, this app is key for that. wish I'd of done a review before. and it's also free so don't worry about that.
Rohan U
Android user
I know a lot of apps use fake accounts to boost their reviews but this app deserves it all. Originally I was getting 4 in my English exams and this time I got a grade 7. I didn’t even know about this app three days until the exam and it has helped A LOT. Please actually trust me and use it as I’m sure you too will see developments.
Xander S
iOS user
THE QUIZES AND FLASHCARDS ARE SO USEFUL AND I LOVE Knowunity AI. IT ALSO IS LITREALLY LIKE CHATGPT BUT SMARTER!! HELPED ME WITH MY MASCARA PROBLEMS TOO!! AS WELL AS MY REAL SUBJECTS ! DUHHH 😍😁😲🤑💗✨🎀😮
Elisha
iOS user
This apps acc the goat. I find revision so boring but this app makes it so easy to organize it all and then you can ask the freeeee ai to test yourself so good and you can easily upload your own stuff. highly recommend as someone taking mocks now
Paul T
iOS user
The app is very easy to use and well designed. I have found everything I was looking for so far and have been able to learn a lot from the presentations! I will definitely use the app for a class assignment! And of course it also helps a lot as an inspiration.
Stefan S
iOS user
This app is really great. There are so many study notes and help [...]. My problem subject is French, for example, and the app has so many options for help. Thanks to this app, I have improved my French. I would recommend it to anyone.
Samantha Klich
Android user
Wow, I am really amazed. I just tried the app because I've seen it advertised many times and was absolutely stunned. This app is THE HELP you want for school and above all, it offers so many things, such as workouts and fact sheets, which have been VERY helpful to me personally.
Anna
iOS user
Best app on earth! no words because it’s too good
Thomas R
iOS user
Just amazing. Let's me revise 10x better, this app is a quick 10/10. I highly recommend it to anyone. I can watch and search for notes. I can save them in the subject folder. I can revise it any time when I come back. If you haven't tried this app, you're really missing out.
Basil
Android user
This app has made me feel so much more confident in my exam prep, not only through boosting my own self confidence through the features that allow you to connect with others and feel less alone, but also through the way the app itself is centred around making you feel better. It is easy to navigate, fun to use, and helpful to anyone struggling in absolutely any way.
David K
iOS user
The app's just great! All I have to do is enter the topic in the search bar and I get the response real fast. I don't have to watch 10 YouTube videos to understand something, so I'm saving my time. Highly recommended!
Sudenaz Ocak
Android user
In school I was really bad at maths but thanks to the app, I am doing better now. I am so grateful that you made the app.
Greenlight Bonnie
Android user
very reliable app to help and grow your ideas of Maths, English and other related topics in your works. please use this app if your struggling in areas, this app is key for that. wish I'd of done a review before. and it's also free so don't worry about that.
Rohan U
Android user
I know a lot of apps use fake accounts to boost their reviews but this app deserves it all. Originally I was getting 4 in my English exams and this time I got a grade 7. I didn’t even know about this app three days until the exam and it has helped A LOT. Please actually trust me and use it as I’m sure you too will see developments.
Xander S
iOS user
THE QUIZES AND FLASHCARDS ARE SO USEFUL AND I LOVE Knowunity AI. IT ALSO IS LITREALLY LIKE CHATGPT BUT SMARTER!! HELPED ME WITH MY MASCARA PROBLEMS TOO!! AS WELL AS MY REAL SUBJECTS ! DUHHH 😍😁😲🤑💗✨🎀😮
Elisha
iOS user
This apps acc the goat. I find revision so boring but this app makes it so easy to organize it all and then you can ask the freeeee ai to test yourself so good and you can easily upload your own stuff. highly recommend as someone taking mocks now
Paul T
iOS user
体積と質量の基本を理解する
物質を理解するために欠かせない「体積」と「質量」について学んでいこう。普段何気なく使っている「重さ」と「質量」は実は違うもので、正確な測り方にもコツがあるんだ。実験でよく使うメスシリンダーや上皿てんびんの使い方をマスターして、テストでも実験でも自信を持てるようになろう！
体積と質量の基本
君たちが毎日使っているものにも、必ず体積と質量がある。体積は物質が占める空間の大きさで、単位は**cm³（立方センチメートル）やmL（ミリリットル）**を使うよ。
質量は場所が変わっても変化しない、物質そのものの量のこと。単位は**g（グラム）やkg（キログラム）**で表す。ここで注意したいのが、普段使う「重さ」とは違うということ！
重さは月に行くと軽くなるけど、質量はどこでも同じなんだ。実験ではメスシリンダーで体積を、上皿てんびんで質量を正確に測ることができる。
覚えておこう！ 1cm³ = 1 mL という関係は計算問題でよく使うよ。
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液体の体積測定とメニスカス
液体の体積を測るときはメスシリンダーを使う。まず水平な場所に置いて、測りたい液体を注いだら、目の高さを液面に合わせて水平に目盛りを読むんだ。
ここで重要なのがメニスカスという現象。液体の表面は、ふちが少し盛り上がって中央がへこんだカーブになる。目盛りは、このへこんだ部分の底を読むのが正しい方法だよ。
見上げたり見下ろしたりすると正確な値が読めないから、必ず目の高さを合わせること。メスシリンダーの最小目盛りも確認して、その1/10まで目分量で読み取ろう。
実験のコツ！ メニスカスの底を読むのがポイント。目の高さを液面に合わせるのを忘れずに！
Sign up to see the contentIt's free!
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Improve your grades
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固体の体積測定法
固体の体積は形によって測り方が変わる。直方体のような形が整っているものは、定規で長さを測って計算で求められる。公式は「体積 = たて × 横 × 高さ」だ。
石ころのような不規則な形の固体は、メスシリンダーと水を使った方法で測る。まず固体が完全に沈む量の水を入れて体積を読み（V₁）、次に固体を静かに入れた後の体積を読む（V₂）。
固体の体積 = V₂ - V₁ という計算で求められる。水がはねないように静かに入れるのがポイントだよ。この方法なら、どんな複雑な形でも正確に測定できる。
計算のコツ！ 増えた分の体積がそのまま固体の体積になる。V₂からV₁を引くだけ！
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上皿てんびんの正しい使い方
上皿てんびんで質量を測るときは、正しい手順が大切だ。まず水平な台に置いて、左右の皿に何も乗せずに針が中央で同じくらい振れるか確認する。
測りたいものを左の皿に乗せて、右の皿にはピンセットを使って分銅を乗せていく。質量の大きい分銅から順に乗せて、針が中央に来るように調整しよう。
絶対に分銅を手でさわってはいけない！ 汚れたりさびたりして質量が変わってしまうからだ。薬品を測るときも、直接皿に乗せず薬包紙を使うこと。
皿に乗っている分銅の質量の合計が、測りたいものの質量になる。左右の皿に同じ大きさの薬包紙を乗せてから測り始めるのも忘れずに。
注意ポイント！ 分銅は必ずピンセットで扱う。手の汚れで測定値が変わっちゃうよ！
Sign up to see the contentIt's free!
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計算問題と実践例
実際の計算問題を解いてみよう。石の体積を求める問題では、メスシリンダーに50.0 mLの水を入れ、石を沈めたら65.0 mLになったとする。
石の体積は 65.0 mL - 50.0 mL = 15.0 mL となる。1 mL = 1 cm³ という関係を使って、答えは15.0 cm³だ。
食塩水の質量を求める問題では、空のビーカーが52.5g、食塩水を入れた全体が113.8gの場合を考える。食塩水だけの質量は 113.8g - 52.5g = 61.3g となる。
このように、全体から容器の質量を引けば中身の質量がわかる。計算の考え方を理解すれば、どんな問題でも解けるようになるよ。
計算のコツ！ 「増えた分」や「差し引いた分」を考えれば、複雑そうな問題も簡単に解ける！
Sign up to see the contentIt's free!
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Improve your grades
Join milions of students
質量と重さの決定的な違い
テストでよく出る質量と重さの違いをしっかり覚えよう。質量は物質そのものの量で、どこにいても変わらない。重さは重力の大きさで、場所によって変化する。
測る器具も違っていて、質量は上皿てんびん、重さはばねはかりを使う。単位も質量はg・kg、重さはN（ニュートン）と区別されている。
月に行くと体重は約1/6になるけど、質量は地球にいるときと全く同じ。この例を覚えておけば、テストで間違えることはないよ。
実験では正確な測定が重要だから、メスシリンダーの読み方や上皿てんびんの使い方をしっかりマスターしよう。練習すれば必ずできるようになる！
テスト対策！ 「月では体重が軽くなるけど質量は同じ」という例で覚えれば完璧！
We thought you’d never ask...
What is the Knowunity AI companion?
Our AI Companion is a student-focused AI tool that offers more than just answers. Built on millions of Knowunity resources, it provides relevant information, personalised study plans, quizzes, and content directly in the chat, adapting to your individual learning journey.
Where can I download the Knowunity app?
You can download the app from Google Play Store and Apple App Store.
Is Knowunity really free of charge?
That's right! Enjoy free access to study content, connect with fellow students, and get instant help – all at your fingertips.
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4.6/5
App Store
4.7/5
Google Play
The app is very easy to use and well designed. I have found everything I was looking for so far and have been able to learn a lot from the presentations! I will definitely use the app for a class assignment! And of course it also helps a lot as an inspiration.
Stefan S
iOS user
This app is really great. There are so many study notes and help [...]. My problem subject is French, for example, and the app has so many options for help. Thanks to this app, I have improved my French. I would recommend it to anyone.
Samantha Klich
Android user
Wow, I am really amazed. I just tried the app because I've seen it advertised many times and was absolutely stunned. This app is THE HELP you want for school and above all, it offers so many things, such as workouts and fact sheets, which have been VERY helpful to me personally.
Anna
iOS user
Best app on earth! no words because it’s too good
Thomas R
iOS user
Just amazing. Let's me revise 10x better, this app is a quick 10/10. I highly recommend it to anyone. I can watch and search for notes. I can save them in the subject folder. I can revise it any time when I come back. If you haven't tried this app, you're really missing out.
Basil
Android user
This app has made me feel so much more confident in my exam prep, not only through boosting my own self confidence through the features that allow you to connect with others and feel less alone, but also through the way the app itself is centred around making you feel better. It is easy to navigate, fun to use, and helpful to anyone struggling in absolutely any way.
David K
iOS user
The app's just great! All I have to do is enter the topic in the search bar and I get the response real fast. I don't have to watch 10 YouTube videos to understand something, so I'm saving my time. Highly recommended!
Sudenaz Ocak
Android user
In school I was really bad at maths but thanks to the app, I am doing better now. I am so grateful that you made the app.
Greenlight Bonnie
Android user
very reliable app to help and grow your ideas of Maths, English and other related topics in your works. please use this app if your struggling in areas, this app is key for that. wish I'd of done a review before. and it's also free so don't worry about that.
Rohan U
Android user
I know a lot of apps use fake accounts to boost their reviews but this app deserves it all. Originally I was getting 4 in my English exams and this time I got a grade 7. I didn’t even know about this app three days until the exam and it has helped A LOT. Please actually trust me and use it as I’m sure you too will see developments.
Xander S
iOS user
THE QUIZES AND FLASHCARDS ARE SO USEFUL AND I LOVE Knowunity AI. IT ALSO IS LITREALLY LIKE CHATGPT BUT SMARTER!! HELPED ME WITH MY MASCARA PROBLEMS TOO!! AS WELL AS MY REAL SUBJECTS ! DUHHH 😍😁😲🤑💗✨🎀😮
Elisha
iOS user
This apps acc the goat. I find revision so boring but this app makes it so easy to organize it all and then you can ask the freeeee ai to test yourself so good and you can easily upload your own stuff. highly recommend as someone taking mocks now
Paul T
iOS user
The app is very easy to use and well designed. I have found everything I was looking for so far and have been able to learn a lot from the presentations! I will definitely use the app for a class assignment! And of course it also helps a lot as an inspiration.
Stefan S
iOS user
This app is really great. There are so many study notes and help [...]. My problem subject is French, for example, and the app has so many options for help. Thanks to this app, I have improved my French. I would recommend it to anyone.
Samantha Klich
Android user
Wow, I am really amazed. I just tried the app because I've seen it advertised many times and was absolutely stunned. This app is THE HELP you want for school and above all, it offers so many things, such as workouts and fact sheets, which have been VERY helpful to me personally.
Anna
iOS user
Best app on earth! no words because it’s too good
Thomas R
iOS user
Just amazing. Let's me revise 10x better, this app is a quick 10/10. I highly recommend it to anyone. I can watch and search for notes. I can save them in the subject folder. I can revise it any time when I come back. If you haven't tried this app, you're really missing out.
Basil
Android user
This app has made me feel so much more confident in my exam prep, not only through boosting my own self confidence through the features that allow you to connect with others and feel less alone, but also through the way the app itself is centred around making you feel better. It is easy to navigate, fun to use, and helpful to anyone struggling in absolutely any way.
David K
iOS user
The app's just great! All I have to do is enter the topic in the search bar and I get the response real fast. I don't have to watch 10 YouTube videos to understand something, so I'm saving my time. Highly recommended!
Sudenaz Ocak
Android user
In school I was really bad at maths but thanks to the app, I am doing better now. I am so grateful that you made the app.
Greenlight Bonnie
Android user
very reliable app to help and grow your ideas of Maths, English and other related topics in your works. please use this app if your struggling in areas, this app is key for that. wish I'd of done a review before. and it's also free so don't worry about that.
Rohan U
Android user
I know a lot of apps use fake accounts to boost their reviews but this app deserves it all. Originally I was getting 4 in my English exams and this time I got a grade 7. I didn’t even know about this app three days until the exam and it has helped A LOT. Please actually trust me and use it as I’m sure you too will see developments.
Xander S
iOS user
THE QUIZES AND FLASHCARDS ARE SO USEFUL AND I LOVE Knowunity AI. IT ALSO IS LITREALLY LIKE CHATGPT BUT SMARTER!! HELPED ME WITH MY MASCARA PROBLEMS TOO!! AS WELL AS MY REAL SUBJECTS ! DUHHH 😍😁😲🤑💗✨🎀😮
Elisha
iOS user
This apps acc the goat. I find revision so boring but this app makes it so easy to organize it all and then you can ask the freeeee ai to test yourself so good and you can easily upload your own stuff. highly recommend as someone taking mocks now
Paul T
iOS user