in this video I'll talk about an elevator problem elevator problem like physics problem so a girl who weighs 500 new turn on a ground level it steps up into an elevator and she finds scissors now 530 Newton did this information enough sufficient to tell the direction of the elevator motion or in other words what is asking is would it be able to tell whether the elevator is going up or it is going down so again the question is a 500 Newton girl on a ground level or when the elevator is not moving steps up in an elevator and the reading is now 530 Newton is this information sufficient to tell the direction of the elevator well the short answer is no it is not sufficient so now let's dig into a detailed explanation of this one how so the weight of the girl is 500 Newton from this information we can find out the mass the mass is M times G and they this mass is fifty one kilogram and the mass does not change whether you are in an elevator or you are in mu or you are on a moon Jupiter it is the same the weight might change so if the elevator is going up let's say for example in this particular situation here if the elevator is going up we're going to apply the Newton's second law of motion what are the Newton's second law of motion tells you is F is equal to Ma and remember this is the net force this is the net force okay that with all the forces in the direction of motion has to be consider all the forces so in this case when the elevator is moving up all that the photo total forces is T which is vertically upward minus mg the mg is downward so that's the net force times M times X a which is the acceleration so if we solve for T what we get is M G Plus a so the first impression that you might get as the as the reading is going up and the reading has increased the elevator must be going up but that's the cast air even the elevator is going up the one time the or the a can be positive or can be negative what does it mean this means that even if the elevator is going up the one time it speeds up from rest to a certain velocity that and when it wants to stop it slows down so the acceleration is positive one time and when it tries to come to a stop Indy accelerates that means the a becomes negative so the tension 1 times Rises and then at one time the Falls now let's take a look into what happens if the elevator is going down when the elevator is going down then the Newton's second law of motion tells you T is equal to M minus G a and again a can be positive or it can be negative even if it is going down so we tune or we can come to any conclusion but just by the information that the tension or the reading has increased we cannot tell whether the elevator is going up or going down now let me convince you through a simulation this is a wonderful simulation so here it is so a portion is an elevator and her weight on to a ground level or on to our in an elevator when it is not moving is thousand done okay so I'm pressing the the let's say we go to the the second floor and here we need to keep an eye on to this one how the velocity changes and how the normal force and this weight changes so let's take a look now it starts going up you see it is going up now now it has risk to the second floor okay so so what is happening here the first the in velocity has a decreased that means the acceleration is positive it is going positive and then the velocity force stays constant and then it has to stop on to the second floor so it starts decreasing now so here the acceleration is positive the acceleration is negative so the weight changing now just take a look onto this one let me start okay again okay let me restart this one okay one more time so we'll go I'll just make this acceleration everything hi so this one is thousand Newton and just keep an eye on to this one the Newton from now 900 Newton so it has changed now again thousand Newton so it has gone one time eleven hundred Newton and then nine hundred Newton so even while it is going up though reading goes up and then goes down again and comes back to the normal of course so now if it is going down what happens let's see again the thousand Newton so again 900 new ten thousand Newton 11 under Newton so the reading has again going down and then going up again because it starts decreasing or the acceleration is negative here and the acceleration is positive here so the conclusion is if if just by reading the the the tension or the apparent weight has increased we cannot tell the direction of the elevator so that's it again if you have any questions or any comments write down in the comment section below and do not forget to share like share and subscribe the channel thank you very much