Shadowing-Übung: Newton's Laws: Crash Course Physics #5 - Englisch Sprechen Lernen mit Video

We've been talking a lot about the science of how things move.

You throw a ball in the air, and there are ways to predict exactly how it will fall.

But there's something we've been leaving out.

Forces.

And why they make things accelerate.

And for that, we're going to turn to a physicist you've probably heard of.

Isaac Newton.

With his three laws, published in 1687 in his book Principia, Newton outlined his understanding of motion, and a lot of his ideas were totally new.

Today, more than 300 years later, if you're trying to describe the effects of forces on just about any everyday object – a box on the ground, a reindeer pulling a sleigh,

or an elevator taking you up to your apartment – then you're going to want to use Newton's laws.

And yes, I'll explain the reindeer thing later.

Newton's first law is all about inertia.

Which is basically an object's tendency to keep doing what it's doing.

It's often stated as an object in motion will remain in motion, and an object at rest will remain at rest, unless acted upon by a force.

Which is just another way of saying that to change the way something moves, to give it acceleration, you need a net force.

So how do we measure inertia?

Well, the most important thing to know is mass.

Say you have two balls that are the same size, but one is an inflatable beach ball and the other is a bowling ball.

The bowling ball is going to be harder to move, and harder to stop once it's moving.

It has more inertia because it has more mass.

Makes sense, right?

More mass means more stuff, with a tendency to keep doing what it was doing before your force came along and interrupted it.

And this idea connects nicely to Newton's second law.

Net force is equal to mass times acceleration.

Or, as an equation, F net equals ma.

It's important to remember that we're talking about net force here, the amount of force left over once you've added together all the forces that might cancel each other out.

Let's say you have a hockey puck sitting on a perfectly frictionless ice rink.

And I know they're not usually perfectly frictionless, but stick with it.

If you're pushing the puck along with a stick, that's a force on it that isn't being canceled out by anything else.

So the puck is experiencing acceleration.

But when the puck is just sitting still, or even when it's sliding across the ice after you've pushed it, then all the forces are balanced out.

That's what's known as equilibrium.

An object that's in equilibrium can still be moving, like the sliding puck, but its velocity won't be changing.

It's when the forces get unbalanced that you start to see the exciting stuff happen.

And probably the most common case of a net force making something move is the gravitational force.

Say you throw a 5 kilogram ball straight up in the air and then, you know, get out of the way, because that could really hurt if it hits you.

But the force of gravity is pulling down on the ball, which is accelerating downward at a rate of 9.81 meters per second squared.

So the net force is equal to Ma, but the only force acting here is gravity.

This means that if we could measure the acceleration of the ball, we'd be able to calculate the force of gravity.

And we can measure the acceleration.

It's 9.81 meters per second squared, the value we've been calling small g.

So the force of gravity on the ball must be 5 kilograms, which is the mass of the ball, small g, which comes to 49.05 kilograms times meters per second squared.

We use this equation for gravity so much that it's often just written as Fg equals mg.

That's how you determine the force of gravity, otherwise known as weight.

Now, those units can be a bit of a mouthful, so we just call them newtons.

That's right, we measure weight in newtons, in honor of Sir Isaac, and not in kilograms.

Kilograms are a measure of mass.

But gravity often isn't the only force acting on the object.

So when we're trying to calculate a net force, we usually have to take into account more than just gravity.

This is where we get into one of the forces that tends to show up a lot, which is explained by Newton's third law.

You probably know this law as for every action there's an equal but opposite reaction, which just means that if you exert a force on an object, it exerts an equal force back on you.

And that's what we call the normal force.

Normal, in this instance, means perpendicular, and the normal force is always perpendicular to whatever surface your object is resting on.

At least, it is when you're pushing on something big and macroscopic, like a table.

If you put a book down on a table, the normal force is pushing, and therefore pointing, up.

But if you put it on a ramp, the normal force is pointing perpendicular to the ramp.

Now, the normal force isn't like most other forces.

It's special, because it changes its magnitude.

Say you have a piece of aluminum foil stretched tightly across the top of a bowl, and then you put one lonely grape on top of it.

Because of gravity, that grape is exerting a little bit of force on the foil, and the normal force pushes right back with the same amount.

But then you add another grape, which doubles the force on the foil.

In that case, the normal force doubles, too.

That'll keep happening until eventually you add enough grapes that they break through the foil.

That's what happens when the normal force can't match the force pushing against it.

But what does Newton's famous third law really mean, though?

When I push on this desk with my finger right now, I'm applying a force to it, and it's applying an equal force right back on my finger – one that I can actually feel.

But if that's true – and it is – then why are we able to move things?

How can I pick up this mug?

Or how can a reindeer pull a sleigh?

Basically, things can move because there's more going on than just the action and reaction forces.

For example, when a reindeer pulls on a sleigh, Newton's third law tells us that the sleigh is pulling back on it with an equal force.

But the reindeer can still move the sleigh forward, because it's standing on the ground.

When it takes a step, it's pushing backward on the ground with its foot, and the ground is pushing it forward.

Meanwhile, the reindeer is also pulling on the sleigh, while the sleigh is pulling right back.

But the force from the ground pushing the reindeer forward is stronger than the force from the sleigh pulling it back.

So the animal accelerates forward, and so does the sleigh.

So one takeaway here is that there would be no Christmas without physics.

Now we have an idea of some of the forces we might encounter, let's describe what's happening when a box is sitting on the ground.

The first thing to do, which is the first thing you should always do when you're solving a problem like this, is to draw what's known as a free body diagram.

Basically, you draw a rough outline of the object, put a dot in the middle, and then draw and label arrows to represent all the forces.

We also have to decide which direction is positive.

In this case, we'll choose up to be positive.

For our box, the free body diagram is pretty simple.

There's an arrow pointing down, representing the force of gravity, and an arrow pointing up, representing the force of the ground, pushing back on the box.

Since the box is staying still, we know that it's not accelerating, which tells us that those forces are equal.

So the net force is equal to zero.

But what if you attach a rope to the top of the box, then connect it to the ceiling so the box is suspended in the air?

Your net force is still zero, because there's no acceleration on the box, and gravity is still pulling down in the same way it was before.

But now the counteracting upward force comes from the rope acting on the box, in what we call the tension force.

To make our example simpler, we almost always assume that ropes have no mass and are completely unbreakable.

No matter how much you pull on them, they'll pull right back.

Which means that the tension force isn't fixed.

If the box weighs 5 newtons, then the tension in the rope is also 5 newtons.

But if we add another 5 newtons of weight, the tension in the rope will become 10 newtons.

It's kind of like how the normal force changes with the grapes on the foil, but in this case, it's in response to a pulling force instead of a push.

The key is that no matter what, you can add the forces together to give you a particular net force, even though that net force might not always be zero.

Like in an elevator.

So let's say you're in an elevator, or as I call them, a lift.

The total mass of the lift, including you, is a thousand kilograms, and its movement is controlled by a counterweight attached to a pulley.

100

The plan is to set up a counterweight of 850 kilograms, and then let the lift go.

101

Once you let go, the lift is going to start accelerating downwards, because it's heavier than the counterweight.

102

And the hope is that the counterweight will keep it from accelerating too much.

103

But how will we know if it's safe?

104

How quickly is the lift going to accelerate downward?

105

To find out, let's first draw a free-body diagram for the lift, making up the positive direction.

106

The force of gravity on the lift is pulling it down, and it's equal to the mass of the lift times small g.

107

9,810 newtons of force in the negative direction.

108

And the force of tension is pulling the lift up in the positive direction.

109

Which means that for the lift, the net force is equal to the tension force minus the mass of the lift times small g.

110

Now, since Newton's first law tells us that F net equals ma,

111

we can set all of that to be equal to the lift's mass times some downward acceleration, minus a.

112

That's what we're trying to solve for.

113

So let's do the same thing for the counterweight.

114

Gravity is pulling it down with 8,338.5 Newtons of force in the negative direction.

115

And again, the force of tension is pulling it up, so that the net force is equal to the tension force minus the mass of the counterweight times small g.

116

And again, because of Newton's second law, we know that all of that is equal to the mass of the counterweight times that same acceleration, a, which is positive this time,

117

since the counterweight is moving upwards.

118

So, putting all of that together, we end up with two equations and two unknowns.

119

We don't have a value for the tension force, and we don't have a value for acceleration.

120

But what we're trying to solve for is the acceleration, so we use algebra to do that.

121

When you have a system of equations like this, you can add or subtract all the terms on each side of the equals sign to turn them into one equation.

122

For example, if you know that 1 plus 2 equals 3, and that 4 plus 2 equals 6,

123

you can subtract the first equation from the second to get 3 equals 3.

124

And in our case with the lift, subtracting the first equation from the second gets rid of the term that represents the tension force.

125

We now just have to solve for acceleration, meaning we need to rearrange the equation to set everything equal to A.

126

We end up with an equation that really just says that A is equal to the difference between the weights, or the net force, on the system, divided by the total mass.

127

Essentially, this is just a fancier version of F net equals ma.

128

And we can solve that for a, which turns out to be 0.795 meters per second squared.

129

Which is not that much acceleration at all.

130

So as long as you aren't dropping too far down, you should be fine.

131

Even if the landing's a little bumpy.

132

In this episode, you learned about Newton's three laws of motion, how inertia works, that net force is equal to mass times acceleration,

133

how physicists define equilibrium, and all about the normal force and the tension force.

134

Crash Course Physics is produced in association with PBS Digital Studios.

135

You can head over to their channel to check out amazing shows like BrainCraft, It's OK to be Smart and PBS Idea Channel.

136

This episode of Crash Course was filmed in the Dr. Cheryl C.

137

Kinney's Crash Course Studio with the help of these amazing people and our graphics team is Thought Cafe.

📺 Gleicher Kanal

Vectors and 2D Motion: Crash Course Physics #4

TOEFL PrepCambridge Exam PrepUniversity Students

What's all the Yellen About? Monetary Policy and the Federal Reserve: Crash Course Economics #10

IELTS PrepBusiness EnglishUniversity Students

Defense Against the Dark Arts of Influence: Crash Course Business Soft Skills #2

Business EnglishUniversity StudentsWorking Adults

✨ Empfohlenes Video

9 Sätze

Walter Lewin explains Newton's third law

Cambridge Exam PrepHigh School StudentsUniversity Students

102 Sätze

Orbital Mechanics - Newton's Laws

TOEFL PrepCambridge Exam PrepUniversity Students

425 Sätze

NEW- Micro Unit 1 Summary- Basic Economic Concepts

Cambridge Exam PrepUniversity Students

75 Sätze

High School Physics: What Is Physics?

Cambridge Exam PrepHigh School StudentsUniversity Students

44 Sätze

Crash Course Physics Preview

Cambridge Exam PrepUniversity Students

114 Sätze

Newton, Leibniz, and Usain Bolt | Derivatives introduction | AP Calculus AB | Khan Academy

Cambridge Exam PrepUniversity StudentsWorking Adults

148 Sätze

First Law of Thermodynamics, Basic Introduction - Internal Energy, Heat and Work - Chemistry

IELTS PrepTOEFL PrepCambridge Exam Prep

44 Sätze

Energy Transformations

TOEFL PrepCambridge Exam PrepHigh School Students

64 Sätze

¿Cómo funcionan las Leyes de Newton? 🍎

Cambridge Exam PrepUniversity StudentsWorking Adults

22 Sätze

States of Matter | Solid Liquid Gas

Cambridge Exam PrepHigh School StudentsUniversity Students

Wortschatz und Sprechhinweise zu dieser Lektion

Diese Sprechübung auf Niveau C1 basiert auf dem Video „Newton's Laws: Crash Course Physics“. Diese Wörter kommen am häufigsten vor: force, equal, net, mass, acceleration. Dieses Video enthält 137 Sätze und 2220 Wörter zum Nachsprechen. Der gesprochene Teil dauert 10:50. Der Sprecher spricht schnell, etwa 205 Wörter pro Minute – rechne mit verbundenen und verkürzten Lauten. 83 % der Wörter gehören zu den 3.000 häufigsten im Englischen; den Rest solltest du dir vor dem Üben ansehen.

Wichtiger Wortschatz in diesem Video

Die 15 anspruchsvollsten Wörter aus dem Video, mit Aussprache und Bedeutung:

Wort	Aussprache	Bedeutung
acceleration Substantiv	/əkˌsɛl.əˈɹeɪ.ʃən/	Beschleunigung, Akzeleration
equation Substantiv	/ɪˈkweɪ.ʒən/	Ausgleich, Gleichgewicht
counterweight Substantiv		Gegengewicht
newton Substantiv	/ˈn(j)uːtən/	Newton
kilogram Substantiv	/ˈkɪləɡɹæm/	Kilogramm
reindeer Substantiv	/ˈɹeɪndɪɹ/	Ren, Rentier
accelerate Verb	/ɪkˈsɛl.əˌɹeɪt/	beschleunigen
grape Substantiv	/ɡɹeɪp/	Traube, Weintraube
foil Substantiv	/fɔɪl/	Folie
rope Substantiv	/ɹoʊp/	Seil, Tau
inertia Substantiv	/ɪnˈɝ.ʃə/	Trägheit, Beharrungsvermögen
meter Substantiv	/ˈmitəɹ/	Messgerät
exert Verb	/ɪɡˈzɝt/	ausüben
perpendicular Adjektiv	/ˌpɜː.pənˈdɪk.jə.lə(ɹ)/	rechtwinklig, lotrecht
subtract Verb	/səbˈtɹækt/	subtrahieren, abziehen

Phrasal Verbs, die du hören wirst

Wort	Aussprache	Bedeutung
break through Verb		Durchbruch
check out Verb		überprüfen
come along Verb		mitgehen
find out Verb		herausfinden, erfahren
make up Verb	/ˌmeɪk ˈʌp/	wiedergutmachen, kompensieren
pick up Verb		aufheben, aufnehmen
set up Verb	/ˌsɛt ˈʌp/	aufbauen, für den Einsatz vorbereiten
show up Verb		auftauchen, erscheinen

Sätze zum Wiederholen

Kurze, vollständige Sätze aus dem Video, die du im Alltag wiederverwenden kannst:

How can I pick up this mug?
In this case, we'll choose up to be positive.
But how will we know if it's safe?
That's what we're trying to solve for.

Grammatik in diesem Video

Die Strukturen, die der Sprecher am häufigsten verwendet, mit den genauen Worten aus dem Video:

Struktur	Im Video
Present Perfect Continuous have/has been + -ing – eine Handlung, die früher begann und noch andauert	We've been talking · we've been leaving · we've been calling
Passiv be + Partizip Perfekt – wichtig ist, was geschieht, nicht wer es tut	being canceled · are balanced · is explained
Present Perfect have/has + Partizip Perfekt – eine vergangene Handlung, die jetzt noch wichtig ist	you've probably heard · you've added · you've pushed
Relativsätze who / which + Satz – eine Zusatzinformation über eine Person oder Sache	ball, which is · kilograms, which is · lot, which is

Aussprache, auf die du achten solltest

Der Sprecher verwendet 33 Kurzformen und abgeschwächte Formen, zum Beispiel you're, we're, isn't. Sprich sie in der kurzen Form, so wie du sie hörst.

Die Laute „sh“ und „zh“: acceleration /əkˌsɛl.əˈɹeɪ.ʃən/, equation /ɪˈkweɪ.ʒən/, inertia /ɪnˈɝ.ʃə/, gravitational /ˌɡɹævɪˈteɪʃənəl/
Lange Wörter – auf die Betonung achten: acceleration /əkˌsɛl.əˈɹeɪ.ʃən/, accelerate /ɪkˈsɛl.əˌɹeɪt/, perpendicular /ˌpɜː.pənˈdɪk.jə.lə(ɹ)/, equilibrium /ɛkwɪˈlɪbɹɪəm/, elevator /ˈɛləˌveɪtɚ/

Laute, die Deutschsprachigen schwerfallen:

/w/ — mit runden Lippen, nicht wie das deutsche „w“ (/v/): equation /ɪˈkweɪ.ʒən/, equilibrium /ɛkwɪˈlɪbɹɪəm/, downward /ˈdaʊnwɚd/, downwards /ˈdaʊnwɚdz/, takeaway /ˈteɪkəweɪ/
Stimmhafter Auslaut — /b/, /d/, /g/, /z/, /v/ am Wortende nicht verhärten: downward /ˈdaʊnwɚd/, downwards /ˈdaʊnwɚdz/, rearrange /ˌɹiːəˈɹeɪndʒ/, suspend /səsˈpɛnd/, upward /ˈʌpwɚd/
/æ/ — offener als „ä“: kilogram /ˈkɪləɡɹæm/, subtract /səbˈtɹækt/, diagram /ˈdaɪ.ə.ɡɹæm/, attach /əˈtæt͡ʃ/, calculate /ˈkælkjʊleɪt/

So übst du mit diesem Video

Höre dir das ganze Video einmal an, ohne zu sprechen, und notiere die Wörter, die du nicht kennst.
Beginne mit 0,75-facher Geschwindigkeit, sprich Satz für Satz nach und wechsle zur normalen Geschwindigkeit, sobald es leichtfällt.
Nimm dich auf und vergleiche mit dem Original; achte dabei auf Wörter wie acceleration, equation, counterweight.

Was ist die Shadowing-Technik?

Shadowing ist eine wissenschaftlich fundierte Sprachlerntechnik, die ursprünglich für die professionelle Dolmetscherausbildung entwickelt und durch den Polyglotten Dr. Alexander Arguelles populär gemacht wurde. Die Methode ist einfach aber wirkungsvoll: Du hörst englisches Audio von Muttersprachlern und wiederholst es sofort laut — wie ein Schatten, der dem Sprecher mit nur 1–2 Sekunden Verzögerung folgt. Anders als passives Hören oder Grammatikübungen zwingt Shadowing dein Gehirn und deine Mundmuskulatur, gleichzeitig echte Sprachmuster zu verarbeiten und zu reproduzieren. Studien zeigen, dass es Aussprachegenauigkeit, Intonation, Rhythmus, verbundene Sprache, Hörverständnis und Sprechflüssigkeit signifikant verbessert — was es zu einer der effektivsten Methoden für die IELTS Speaking-Vorbereitung und reale englische Kommunikation macht.

Shadowing-Technik: die vollständige Schritt-für-Schritt-Anleitung lesen →

Shadowing-Übung: Newton's Laws: Crash Course Physics #5 - Englisch Sprechen Lernen mit Video

Vectors and 2D Motion: Crash Course Physics #4

What's all the Yellen About? Monetary Policy and the Federal Reserve: Crash Course Economics #10

Unit Conversion & Significant Figures: Crash Course Chemistry #2

What Is Myth? Crash Course World Mythology #1

Mesopotamia: Crash Course World History #3

Crash Course Sex Ed Preview

The Agricultural Revolution: Crash Course World History #1

Derivatives: Crash Course Physics #2

Indus Valley Civilization: Crash Course World History #2

Ancient Egypt: Crash Course World History #4

What is Engineering?: Crash Course Engineering #1

The Persians & Greeks: Crash Course World History #5

Supervised Learning: Crash Course AI #2

The Periodic Table: Crash Course Chemistry #4

How Often do Asteroids Hit the Earth?: Crash Course Geology #20

Where Do Diamonds Come From?: Crash Course Geology #8

Why You Need Trust to Do Business: Crash Course Business - Soft Skills #1

Where Did Democracy Come From, and Does It Still Work?

The Nucleus: Crash Course Chemistry #1

Defense Against the Dark Arts of Influence: Crash Course Business Soft Skills #2

Walter Lewin explains Newton's third law

Orbital Mechanics - Newton's Laws

NEW- Micro Unit 1 Summary- Basic Economic Concepts

High School Physics: What Is Physics?

Crash Course Physics Preview

Newton, Leibniz, and Usain Bolt | Derivatives introduction | AP Calculus AB | Khan Academy

First Law of Thermodynamics, Basic Introduction - Internal Energy, Heat and Work - Chemistry

Energy Transformations

¿Cómo funcionan las Leyes de Newton? 🍎

Gravity Explained Simply

States of Matter | Solid Liquid Gas

Wortschatz und Sprechhinweise zu dieser Lektion

Wichtiger Wortschatz in diesem Video

Phrasal Verbs, die du hören wirst

Sätze zum Wiederholen

Grammatik in diesem Video

Aussprache, auf die du achten solltest

So übst du mit diesem Video

Was ist die Shadowing-Technik?