Normal force in an elevator | Forces and Newton's laws of motion | Physics | Khan Academy

How the normal force changes when an elevator accelerates. Created by Sal Khan.

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.

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[KoolThing]

"We're only going to talk about vertical direction" Glad to know we're not dealing with Willy Wonka's GLASS elevator.

[susie]

am i the only who is thankful that his 2yr old son was interested in elevators

[artakisthebest]

this is SOOO intuitive when trying ot udnerstand newtons second law of motion. Constant velocity = no net force, which totally explains why you feel nothing in an elevator going at constant velocity! Initially I struggled to completely grasp the idea, now it is mine, my mind has accepted it, thanks so much sal

[TotoDG]

Sal: “My two-and-a-half year old son is _obsessed_ with elevators”

DieselDucy: “My true successor.”

[sunidatheshorty]

You have just saved my for my IB mock exams! All of your videos were very helpful and thanks a lot!!! :)

[UltraHDViews]

Simple "when the elevator accelerates your weight increase because of an increase in normal force and when the elevator decelerate normal force decreases and you feel light".

[violingirl]

Saved me future frustration on homework in physics class, thank you so much for this video

[mohfa]

Thank you khan academy for your great video lessins.
I have a questiin pls : when the elevator was accelerating the net force was 20N upward, so shouldnt the person feels lighter since the net force is pushing him upward?? .
Thank you in advace

[FlorieS]

The Khan Academy voice is a core youth memory.

[мир-нлх]

this was an interesting lesson!!! Thanks so

[SRTK]

I will be understand more, If you were our teacher!!

[gargichaturvedi]

Thank you for the video.
I had a doubt regarding this.
If I am having an acceleration in the downward direction greater than acceleration due to gravity (> g), what will happen to the body?
According to the textbook, the body inside the elevator would start to fly inside the elevator.
But if we consider the forces in a situation where the lift accelerates with 2g in the downward direction, the normal force comes out to be N = -mg, which I am not able to visualize that easily. Kindly explain.

[danfireflames]

Omg this is awesome!! My physics teacher is so incompetent this will SAVE me! Thanks so much.

[roseb]

to clarify when you say how you feel are you referring to the force of the normal? the counteracting force to the downward force ( not the net force)

[SparkleSprinkly]

I love you... thank you for this video!

[abhishek]

what you have studied is g positive in downward direction and velocity is taken always positve..but here we always take g negative and positive v if it is in upward direction and negative v if it is downward direction...It does matter which method you use because finally negative sign will cancel.

[TheDbzgtaf]

Assuming the frictional force between them to be zero, what would happen if you pushed a block against a wall? How much force do you need to apply so it's stationary? Note: the force applied and the wall and everything are perpendicular to the earth's surface.

[Peter_]

If you jump in an elevator you would still fall down with the elevator's velocity minus your own jumping velocity.
Then immediately after that you will be subject to gravity again and eventually reach normal falling velocity.

[lubime]

@Makro80 :
With all you respect I did not try to critize you excellent and educated videos; I just try to be more helpful than anything else.
I apreciated your effort and the good intension of your videos.
Thanks.

[erikafisher]

In the second example, the normal force is acting on the person at their center of gravity to move them, within the system, upward. Just to be clear, that normal force is increasing as a result of the torque on the pulley system (and the friction of the coil, and the force of gravity on the system as well) bringing the elevator upward right? So the pulley system has ungone an increase of torque to bring the system in the upward direction. The person within the system, is also subject to that same amount of force. Like in a car accident, that every object within the vehicle is subject to the same amount of force that the system (car) itself is subject to, so that if the car comes to a sudden stop, everything in the car continues to move until Newton's first law is "satisfied" and everything comes to a stop?
So technically, if an elevator was moving Upward really quickly, and the elevator had no top (think Willy Wonka minus the glass roof), and the elevator came to a sudden stop, that the person inside said elevator would be subject to the same amount of torque the pulley system was subject to, in an upward motion?
If I am correct, even in a super simplified view, because I am pretty new to this, that is wild 8O