Balanced and unbalanced forces | Forces and Newton's laws of motion | Physics

Balanced and unbalanced forces | Forces and Newton's laws of motion | Physics | Khan Academy

Рет қаралды 504,943

12 жыл бұрын

Courses on Khan Academy are always 100% free. Start practicing-and saving your progress-now: www.khanacademy.org/science/p...
Primer on identifying balanced and unbalanced forces. Created by Sal Khan.
Watch the next lesson: www.khanacademy.org/science/p...
Missed the previous lesson? www.khanacademy.org/science/p...
Physics on Khan Academy: Physics is the study of the basic principles that govern the physical world around us. We'll start by looking at motion itself. Then, we'll learn about forces, momentum, energy, and other concepts in lots of different physical situations. To get the most out of physics, you'll need a solid understanding of algebra and a basic understanding of trigonometry.
About Khan Academy: Khan Academy offers practice exercises, instructional videos, and a personalized learning dashboard that empower learners to study at their own pace in and outside of the classroom. We tackle math, science, computer programming, history, art history, economics, and more. Our math missions guide learners from kindergarten to calculus using state-of-the-art, adaptive technology that identifies strengths and learning gaps. We've also partnered with institutions like NASA, The Museum of Modern Art, The California Academy of Sciences, and MIT to offer specialized content.
For free. For everyone. Forever. #YouCanLearnAnything
Subscribe to Khan Academy’s Physics channel: / channel
Subscribe to Khan Academy: kzfaq.info_...

Пікірлер: 108

@JP.Q 12 жыл бұрын

It's perfectly valid. That's because the friction always works in the opposite direction of the motion. The fact that Sal said that the friction was pointing to the left sort of gives away that the boulder is going to the right, though.

@meganewsindia8594 6 жыл бұрын

.Balance forces are two forces acting in opposite directions on an object, and equal in size. Anytime there is abalanced force on an object, the object stays still or continues moving continues to move at the same speed and in the same direction.

@CNAPART 5 жыл бұрын

"The rock is green...the rock is brown...the rock is resting on the ground"

@Panondras55 7 жыл бұрын

Thank you very much for this videos....they are AWESOME!!!

@shadow3191 12 жыл бұрын

I get it now. It makes sense in hindsight. Thanks.

@barzanaziz7014 2 жыл бұрын

2021 and still the best vid I have watched today

@Lalsiamk 8 жыл бұрын

Dwayne johnson approved this video

@thenigelverse1130 7 жыл бұрын

Lalxiam Khuptong Lol

@StealthyCrab 4 жыл бұрын

haha

@adediwuratayo6887 4 жыл бұрын

Haha lol

@torber5655 4 жыл бұрын

The rock is brown 4:01

@RMSnotTitanic1993 10 ай бұрын

LOLOLOLOL😂

@Chezne_ 12 жыл бұрын

i understood it you made it really simple

@Jonnemanne 12 жыл бұрын

Hi Sal, and thanks a million for such a wonderful library of videos. However, could you possibly number/otherwise categorize the videos on your channel? It's sometimes hard to know which playlist your recently uploaded videos belong to. Greetings from Finland!

@sridhartirunagari2966 6 жыл бұрын

super very clear explanation

@peterbuluma2370 4 жыл бұрын

I lv the way you teach

@JP.Q 12 жыл бұрын

Yes, that's what I understood. The person on the right pushes with 1N and there's an additional 2N due to friction, adding up to 3N.

@erikafisher2934 3 жыл бұрын

How do you know what the force of the static friction acting on an object will be in order to figure out exactly how much force needs to be applied to move the object?

@maggies4839 10 жыл бұрын

You helped out so much! Thank you!

@rahultulsyan6697 Жыл бұрын

hi sal really loved your explanation helped so much

@Bonnet_girl68 3 жыл бұрын

I'm watching this for a test :)

@AlexGonzalez-ve5cv 3 жыл бұрын

Same

@bagyocookies6675 6 жыл бұрын

Dis is kewl

@japie11234 11 жыл бұрын

Thanks so much, this helped my understand unbalanced forces just before my Physics exam :D

@BareClause 12 жыл бұрын

Finally, some Physics videos. You haven't made them in ages.

@shehrima 12 жыл бұрын

شكرا

@prgalois 12 жыл бұрын

Excellent video! Thanks for sharing.

@elfielaurie6588 7 жыл бұрын

this video helped me so much!

@MercifulAreWe 12 жыл бұрын

Another question: For the bottom right picture, since you are adding 1N to the regular 2N of friction, would you not add 2N again but this time to the 4N of friction because the little guy is pushing also?

@nalinichuraman795 6 жыл бұрын

MercifulAreWe the little guy is pushing for 1N and that's already accounted for when Sal added the 1N to 2N force of friction

@eirihalv 12 жыл бұрын

The force of gravity (g) is drawn from center of mass. However, the normal force (n) should be drawn from where the force is beeing applied (between the rock and ground).

@yuri778 12 жыл бұрын

Needs more Lubricon VI.

@StealthyCrab 4 жыл бұрын

legend thx man

@jakirhossen6178 3 жыл бұрын

I get it now....thanks...🇧🇩🇧🇩🇧🇩🇧🇩🇧🇩🇧🇩🇧🇩🇧🇩🇧🇩🇧🇩🇧🇩🇧🇩🇧🇩🇧🇩🇧🇩🇧🇩🇧🇩🇧🇩

@gracysingh7645 8 жыл бұрын

But shouldn't the force of friction act against the little orange man too, I mean the force towards the right should be 5 N ????

@yusuf.s5953 3 жыл бұрын

@Sebastian Carbajal Gomez not gonna fall for it

@yusuf.s5953 3 жыл бұрын

BUT STIIL the purple guy wins the rock pushing competition

@daltonbrua8068 3 жыл бұрын

No, because the rock was not gonna move anyway, he was pushing at 1N and the rock's friction was 2N. The little guy just makes it harder for him.

@hyutghjkfcghbjumklnbhjvy Жыл бұрын

wooow very info

@hyutghjkfcghbjumklnbhjvy Жыл бұрын

yes very info

@TheMsAverage 12 жыл бұрын

I love you mahn.. I freakin love you!

@sergelacasse910 Жыл бұрын

Question: since the rock has a mass, why isn’t there a Normal force acting at the opposite direction of the guy pushing? I believe this is two surfaces, no? So if there’s friction, that would mean the normal force would be whatever Force the guy is pushing in the opposite direction PLUS the force of friction, also in the opposite direction. Does that make sense? So, for example, in the second scenario, the normal force on the x axis would be -4N. Or should we also count the guy’s force of friction in the positive x direction? In other words, I’m mixed up…. :)

@Kram1032 12 жыл бұрын

Yeah, that makes sense but how does it add up with the person pushing against the movement? Is that person's force-vector already partially the 2N Force of friction? In that case, the person only pushes with 1N, right?

@juanpedro19840914 12 жыл бұрын

Because the rock is moving to the right, so the force of friction acts to the opposite direction. i.e. if both guys were applying equal forces, there would not be any friction force. ;)

@Svenskivsk 12 жыл бұрын

since the overall acceleration is to the right friction will only oppose this motion

@meishajones5042 3 жыл бұрын

what if you have a square that has all different numbers for example top is 10N bottom is 5N right is 3N and left is 12N. Do you solve up and down first and left and right second?? Would the answer be 5n with a direction of up and 9N with a direction going left?

@Kram1032 12 жыл бұрын

Ok, then it makes sense. Didn't seem quite clear to me from how Sal presented it.

@ruchipundir9191 3 жыл бұрын

2.09 why should the force of friction be 2N

@nextblain 12 жыл бұрын

please make advance Lagrangian and Hamiltonian mechanics vids , and and quantum mechanics, quantum field theory, QED, strings omfg i am so excited finally some physics omfg *dies of heart attack*

@AdityaSingh-ht6nq 4 жыл бұрын

Hii

@AdityaSingh-ht6nq 4 жыл бұрын

From where are you

@shadow3191 12 жыл бұрын

Correct me if I'm wrong, but wouldn't the second guy pushing the rock also be impeded by friction? I know that even with that, it will be unbalanced, but I just wanted to raise a point.

@toffee7106 3 жыл бұрын

the rock is green.... the rock is brown... haa the rock is resting on the ground HAHAHAHHAHA best part

@tintisor 12 жыл бұрын

thank you

@tintisor 12 жыл бұрын

Question: in last scenario, why isn't the force of friction affecting both guys the same way?

@crsubramani2529 4 жыл бұрын

Because frictional force acts opposite to direction of motion

@danny7921 3 жыл бұрын

I was thinking the same thing too

@erikafisher2934 3 жыл бұрын

Also, last example at the end of the video. You have to people pushing against eachother, 4N to the left, 3N to the right, so the net is 1N to the left, but what about the 2N of friction to the left? Is this just no longer a factor when people become a factor? Should the 2N of friction not also be accounted for and the net be 3N to the left?

@rabeeaanwar6518 2 жыл бұрын

3N is the sum of two forces, one from person i.e 1N and 2N of air friction

@user-rk1ly3yz4p 4 жыл бұрын

Thank you it’s so awesome and I understand in easy way 😍😍😍

@bindurajbanshi9479 Жыл бұрын

6:38

@MercifulAreWe 12 жыл бұрын

So friction is only created when we try to move, or move something? It is not just there?

@greatvaluebleach7384 7 жыл бұрын

When you are sitting down, you have inertia. Friction only works when you are in motion, it slows you down. So when you have inertia, until a force acts upon you, you cannot be slowed down if you are already stationary.

@juld55 12 жыл бұрын

"QFT and strings" Sorry, but that's a little far-fetched. Intro QM and general relativity is do-able though.

@Kram1032 12 жыл бұрын

That's some weird friction, only going against the one guy but not against the other one. (Scenario 5)

@roopsaroy5874 3 жыл бұрын

If two unequal forces are applied on an object in opposite directions, then. Sir can you help me with this 😫

@roopsaroy5874 3 жыл бұрын

@Unicorn Unicorn Thanks a lot 😊

@nextblain 12 жыл бұрын

khan knows everything!!! X)

@chelseacarranza4536 6 жыл бұрын

So wich one of these is the unbalanced

@khaleeldudekula1335 4 жыл бұрын

Cute

@GreAse0MonKey27 Жыл бұрын

At 4:07 I expect Sal saying that's not Brown..

@reyartizona6573 6 жыл бұрын

Can this be an free body diagram?

@SohailKhan-kh2ch 5 жыл бұрын

@chemistrylearner2096 10 ай бұрын

Please use dark colour

@temilonge1349 2 жыл бұрын

this is the easiest video and simple video khan academy has every made.

@isaacsubritzky614 11 жыл бұрын

hi evry one!!!!!!!!!!!

@poshinikrishnamoorthy3060 Жыл бұрын

😊

@AAASSS-su9gy 8 жыл бұрын

if i have pushed a rock with 1n and it has friction of 2n what is going to be the case?

@mahaagro7783 8 жыл бұрын

I don't know if such a scenario is possible. if you're apply 1N force on it and the force of friction is twice as much: 1N-2N= -1N which means the object will accelerate opposite to the direction of your force. But the force of friction opposes motion, it does not create it( then again I'm not an expert either)

@AAASSS-su9gy 8 жыл бұрын

+Maha Agro thank you anyway 😊

@anishjayant1237 6 жыл бұрын

You would not move at all. Maga Agro, that doesn't make sense because thene everything would be accelerating in some direction if noting is hapenning,

@KripticalStudios 3 жыл бұрын

You sound like TheDevKing...

@Authenictruthoid 12 жыл бұрын

Unbalanced forces answer "Washington, DC!!!!!! LoL,Lol That really is the answer. LOL

@alexandrarollar4362 3 жыл бұрын

whats the definition of net force???

@jas1680 3 жыл бұрын

Net force is the vector sum of forces acting on a particle or body. For example, the pictures that are being drawn on the video above.

@PikminDS 12 жыл бұрын

In the fifth scenario shouldn't there be friction counter-acting the push to the left?

@RUDY-by9mz Жыл бұрын

@alondramarizancleto3826 5 жыл бұрын

Ok me desespero este video un poqui

@Sarahhhh18 5 жыл бұрын

VERDAD

@juld55 12 жыл бұрын

It not that he would have trouble learning it himself (which, in all likelihood, he would), it's the absurd amount of time and effort that would have to be put in to making the relevant videos. It would consume all of his time, and probably only a handful of people would end up watching them anyway.

@Mariouigi Жыл бұрын

Look at him now

@udayrithvik5387 3 жыл бұрын

What your class english laja ka

@fizzatariq9742 4 жыл бұрын

kindly use brighter colored pens

@sherlockfury 12 жыл бұрын

wtf is natural force? the rock moves the earth; only its motion is basically imperceivable.

@sharankaur5276 6 жыл бұрын

😴😴😴😴😴

@vengeance9738 4 жыл бұрын

I'd like to think the guy on the right in the 5th example gets squashed over by the rock xD Btw who's watching in December 2019?

@simonhashman1645 3 жыл бұрын

not me

@jmunoz1996 7 жыл бұрын

Rti

@adediwuratayo6887 4 жыл бұрын

I have the app on my phone Why am I stressing myself

@joshuadauzat5559 6 жыл бұрын

omfg , thanks for showing all us 3 year olds how to play add/subtract with numbers 1-5. jesus.. ..

@TaHa-qe7fp 6 жыл бұрын

Flick off hater

@udayrithvik5387 3 жыл бұрын

Bully pa tu ok

@jagjeevannikkam8307 3 жыл бұрын

First speak correct ok

@marce1812 6 жыл бұрын

boring

@TaHa-qe7fp 6 жыл бұрын

marce1812 it is meant for educational purposes not fun

@sanketmaheshwari448 6 жыл бұрын

Ap ki voice isn't nice

@CannibalWarthog 4 жыл бұрын

Video needed to start at minute 5 when you had all of the diagrams drawn already. You repeating yourself a million times just to fill the silence while you draw your diagrams is highly distracting and a waist of time. Draw the diagrams CLEANLY PRIOR and then record the video while getting straight to the point.