# Newton’s Three Laws of Motion

Hi. This is Mr. Andersen. And
today I’m going to be talking about Newton’s Three Laws of Motion. And today is a perfect
day to talk about that. Because when it starts to snow and the roads get icy, you really
start to understand how objects are effected by Newton’s Three Laws of Motion. So I hope
you enjoy. Some would argue that the greatest scientist of all time is this guy, Sir Isaac
Newton. He was clearly a genius. He summarized all of his decades of work in the the Principia,
which some would argue is the greatest book, scientific book ever written. It kick started
physics. In fact it is, most of the formulas in a typical physics book come right out of
this. He also explained gravity and how universal gravitation worked. And then quantified the
movement of the planets. And summarized the work of Kepler. You’re maybe familiar with
the story that somehow an apple fell out of a tree and hit him on the head. That’s probably
not a true story. That didn’t somehow bring about his genius, but he definitely referenced
that in some of his work. And so let’s go through Newton’s laws of motion. First law
is sometimes referred to as the law of inertia. It reads this way. Every body remains in a
state of rest or uniform motion unless acted on by an external unbalanced force. This kind
of summarizes the work of Galileo. What it means is that all objects that are at rest
or in motion have a certain amount of inertia. And that never changes. And so let me give
you an example of that. Let’s say I were to make a magical apple. And then let go of the
apple. The apple would fall down. And the reason why is gravity is pulling it towards
the earth. And so it’s hard to see Newton’s laws of motion with gravity and friction and
air resistance kind of at play. And so I’m going to use my imagination to get rid of
gravity and friction and air resistance. And so now I have a magical place where we can
study Newton’s laws of motion. So let me make that apple again. Okay. So now I’ve got an
apple. And if I let go of the apple, it will just sit there. And the reason it just sits
there is because Newton’s first law of motion. It’s an object at rest. And so it will remain
at rest. Now it will remain at rest until it’s acted on by an external unbalanced force.
What does that mean? Well I could push on that apple from both sides. As long as I’m
pushing on it with the same force from either side, it’ll remain there as well. If I apply
an unequal force. Let me try an unequal force to the apple. Then it will start to spin.
And the reason why is I’ve applied a unbalanced force. So let’s bring gravity back for a second.
And get rid of that apple. Now that’s only one part of it. That an object at rest remains
at rest. Let me take another apple. And this one I’m going to give a little push. And that
apple will move off the screen. And the reason why is it’s an object in motion. And it will
remain in motion. And so that apple, that virtual apple it’s just going and going and
going. And it will go on for ever according to Newton’s first law of motion. And so again.
If you are at rest you’ll remain at rest. If you’re in motion, you’ll remain at motion
unless you get acted on by an unbalanced force. And that’s Newton’s first law of motion. Where
have you experienced this before? Great example would be the toilet paper example I give.
If you want to get paper off of a toilet paper roll, but you can only use one hand, you can
use the law of inertia. If you were to somehow pull the toilet paper very slowly, it’s not
going to help you. And that’s because there’s a lot of friction. But what you can do is
you can grab a little bit of toilet paper and if you quickly move, the inertia of the
toilet paper roll will hold it in place and you can get some of that toilet paper off.
So that’s Newton’s first law of motion. Let’s go to Newton’s second law of motion. Newton’s
second law of motion is arguably the most important of the laws. And the reason why
is that we get a number of formulas that come off of that that we can use to actually measure
how objects move. So what is it? The acceleration of an object is directly proportional to the
force acting on it and inversely proportional to its mass. So what does that mean? Well
the best way to remember the second law of motion is this equation up here. Where force
is equal to mass times acceleration. So let’s make a mass for a second. So I’m going to
make a weight like that. Okay. So now we’ve got a weight here. And so I can apply a force
to a weight. And so let me apply a force to a weight from this side. And I can make that
weight accelerate. Now let’s make a weight that’s a little bit larger. So if I make a
weight that’s a little bit larger, and now I apply that same force to it, it doesn’t
accelerate as quickly. And the reason why is that if I have a bigger mass and I apply
the same force to it, I’m going to get a slower amount of acceleration. And so we can use
that equation to actually do some calculations. And I’ll do that in a separate podcast. Know
this. That if I apply a force in this direction that’s a vector. It’s in a direction. It’s
a magnitude in a direction, I’m going to get that acceleration in the same location. So
I could keep for example my mass the same. So if I keep the mass the same of a weight,
and now I apply a greater force to it, I’m going to get a much greater acceleration.
So that’s Newton’s second law of motion. Let’s go to Newton’s third law of motion. Newton’s
third law is sometimes referred to as the law of action reaction pairs. For every action
there is an opposite and equal or equal and opposite reaction. What does that mean? Well
when I push on something, like if I were to push against a wall, not only am I pushing
against a wall, but the wall is pushing back at me. And you might think that’s kind of
silly. But try pushing against a wall when you’re sitting on a skate board. And you’ll
find that when you push in that direction the wall is going to push you equally in the
opposite direction. Where is this important in Newtonian physics? Well rockets use this
to launch themselves. And so let me make a rocket for example. So I made a rocket right
here. And let me turn it in this direction. So we don’t have gravity. And I’m going to
let it go and just let it hover there. Now in order for a rocket to work, the way that
works is that I can apply a force in this direction. So that’s the fuel that’s coming
out of a rocket when you actually launch it. And then, so that would be an action or force
in this direction. And I’m going to get an equal force in the opposite direction. And
so if I apply a force by lighting that rocket, it’s going to shoot out jet fuel in this direction
and we’re going to get a reaction in the opposite direction. So let’s try that. So that’s Newton’s
third law of motion. Remember for every action there is an opposite and equal reaction. And
so that’s Newton’s laws of motion. They essential govern the way objects move. But you can’t
always see it. And the reason why is that friction tends to get in the way. And so if
you can get rid of friction you can let Newton take over and sit back. I hope that’s helpful.

## 63 thoughts on “Newton’s Three Laws of Motion”

• ### Interactive Biology Post author

Great illustrations of Newton's three laws. Love the animations ๐

• ### Neeboopsh Post author

i wish my science teachers were as good as you. my science teacher in 10th grade had to be corrected by students such as myself all the time. I lost interest in scholastics and dropped out. I would like to think i would have done it differently if i had useful teachers that kept the materials interesting

• ### janice joplin Post author

i honestly watch this bc i find you quite attractive…total plus that i can learn too!! ๐

• ### Abraham Im Post author

Awesome apple!!

• ### Annabelle Eliza Post author

Thank you for all of your videos:) My teacher is hopeless and I've learnt more from you in about half an hour than I've learnt from my physics teacher in two weeks.

• ### Cody Morrissey Post author

Interia is the resistance to change In velocity. Ugh friction and gravity make things so much more complicated to lunderstanding physics. Weight is not massi it is actually te measurement of how much force is exerted on a object by gravity due to its mass ( the amount of matter). The more mass , the more resistance to change in velocity(( inertia)

• ### Sathvik Reddy Daaram Post author

Nice!

Thank you for your lessons. I'm a science teacher in HS. When I'm absent, I always have a clueless SUB. IT is videos like these that I have my students watch when I cannot be there. I also sometimes direct students to watch videos like yours as HW assignments for review. I even sometimes use your videos in class as a preview before I go over the material for something different. Keep up the great work!

• ### DoubleFishers Post author

Im in Mrs. Bouhaider's Class! Block 3

Me toooooooo

block 8

• ### stripeytapir Post author

The Top Gear clip at the end just made the whole video :>

• ### Pierson Ngo Post author

last time i tried to pull on toilet paper really fast with one hand, it didn't rip and i got 8 feet of toilet paper on the floor ๐

• ### Raymond Sarreal Post author

It was a cool presentation. Hahahaha. Not so boring

• ### ํ์์ฐ Post author

Lol, the car at the end

• ### gene546 Post author

man, don't take me wrong but his physics don't work in the universe as a whole, so no he is not the best.

• ### vTanker Post author

1st for St Joes

• ### WhaleOfWar Post author

2nd for St Joes

• ### Nativeinak Hensley Post author

I think this works greatย

• ### NicM Post author

Does this work with green apples as well?

• ### Some Small Fish Post author

I paused at 1:56 and it looks like Mr. Anderson is a little afraid.. o_O

• ### my identity is in Christ Post author

simple yet very clear! thank you so much!

• ### Sarah Davis Post author

This is so awesome! Thanks so much!

• ### Bernadette Gรณmez Post author

Hey there Mr. Anderson! ย I am trying so hard to get a job, but have to demonstrate that I can make videos like yours. ย I'm a public school teacher, and need some help. ย I saw that you used the product phun but it doesn't work on MAC, so I can't use it. ย How is it that you can write or activate circling information on "Powerpoint"? and also get your face on camera during your powerpoint? ย Is it a movie that you film yourself in and then upload? ย Can you give me some hints please about how to create my on-line classroom as you do PLEASE? ย What software programs do you recommend? ย Thank you! B Gomez

• ### OsmarH Post author

LOL. Thanks man. Taking physics again after 13 years and you just woke me up! xD

• ### Geeta Mohammed Post author

Bozeman Science…..GREAT JOB

• ### R.N Post author

u have done a great job i understands every single thing on it
thank u very much for ur hard work

• ### Blas Hernandez Post author

Thank you sir. You have outdone yourself again.

• ### Nilavazhagan cibi Post author

thank u a lot…

• ### Rushil Sudunagunta Post author

fix the camera the lighting is terrible….

• ### Thauhir Benjamin Post author

thx. you helped me under stand newtons second law

• ### VIKASH SAKTHIVEL Post author

๐๐๐๐๐๐๐๐๐ easily understandable.

• ### MrDANO59 Post author

gravity was a movie

• ### Juan Perez Post author

wait, so teh apple from the tree was a lie? illuminat iconfirmed

• ### Oxin vort Post author

Very informative video, thanks!

• ### Anika Haq Post author

Thank you sir.

• ### Benny Post author

siq edit brav

• ### ultimate pirate Post author

sir i'm a little confused
for every force i exert i end up with an opposite and equal force then how can i even have a resultant force if force pairs always cancel each other out?

• ### Anish Tiwari Post author

You are one of the best teachers!

• ### guero*21 Post author

Will a drone flying upwards be an example of newtons 3 law of motion?

Sub to me

• ### TheDarkerElf GAMING Post author

This video sucked

• ### TheDarkerElf GAMING Post author

But you can do better

• ### TheDarkerElf GAMING Post author

Did newton die from the apple

#mendenhall

• ### Krypto Knight Post author

His jawline could cut a bitch

• ### Anthony Olson Post author

Are you sure it's not A=mf because in order to get the acceleration of an object, it would depend on the mass and the force applied to the object!

• ### Anthony Olson Post author

3:34 who else tried this experiment while taking a crap?

• ### Karima Altidor Post author

thanks very simple

thx

• ### Benโs Art Post author

Galileo Figaro๐๐ …huuuu ๐๐

• ### Luke Martin Post author

Begone THOT!!! U do not no de wei

• ### 8bitsorcerer Post author

hello .. I need people's opinion about this… A \$10.00 bet is on the line.. a question with only two answers both of which I think are wrong on their own. here is the question

QUESTION:a person is driving a car forward with his friend that is in the passanger seat. the driver suddenly jerks the steering wheel left….. does the window hit the passanger's head or does the passanger's head hit the window?

LEE: the window pushes into the passanger's head F=MA.

KEN: BOTH happen. the passanger's head hits the window AND the window hits the passanger's head. they both hit each other. newton's 3rd law applies (every action has an equal and opposite reaction..so the answer is neither fully the head hitting the window or the window hitting the head as both must happen .. the question is fallacious the fallacies : AFFIRMING A DISJUNCT AND/OR ALTERNATIVE ADVANCE

• ### Pravin Pandey Post author

um which language is newton's book written in?

• ### Sammie Post author

THE ENDING ๐ญ๐ญ๐

• ### Christyan Brown Post author

i think this was great, nice work. Also is it just me or does he sound a little low???

• ### Mohamed Mohamed Post author

Can you come to Champion Middle School? Cause we watched all of your videos.

4:36

• ### Hayden Clowdus Post author

anyone else chilling in hool not even listening to it

• ### MuShroom Me Post author

0 out of 10. I canโt break these laws.

• ### Muhammad Zafar Post author

Thank you, Mr. Andersen. It helped a lot understanding the laws of Newton. Enormous respect for you after 8 years.

• ### Sudeshna Chaudri Post author

Dr, Anant Chaudri talking to daughter in law, Sudeshna.

My grand son, 18 months old, very good at reciting nursery rhymes was watching his milk bottle next to him for a few minutes. He waited. for some time. He was still. I was wondering what was going on.

He then moved the milk bottle about one foot away and waited, .My curiosity increased.

He then rolled the bottle to hit the wall. Waited and waited for several minutes. I asked him what he was doing. He said he was waiting for his bottle to roll back to him.

Then had his milk and started playing with his toys.

I realised that he was trying to confirm Newtons laws of motion.

I felt in my mind that this chap should have been born 300 years ago