# What is Elevator: Definition and 567 Discussions

An elevator (North American English) or lift (Commonwealth English) is a type of cable-assisted, hydraulic cylinder-assisted, or roller-track assisted machine that vertically transports people or freight between floors, levels, or decks of a building, vessel, or other structure. They are typically powered by electric motors that drive traction cables and counterweight systems such as a hoist, although some pump hydraulic fluid to raise a cylindrical piston like a jack.
In agriculture and manufacturing, an elevator is any type of conveyor device used to lift materials in a continuous stream into bins or silos. Several types exist, such as the chain and bucket elevator, grain auger screw conveyor using the principle of Archimedes' screw, or the chain and paddles or forks of hay elevators. Languages other than English, such as Japanese, may refer to elevators by loanwords based on either elevator or lift. Due to wheelchair access laws, elevators are often a legal requirement in new multistory buildings, especially where wheelchair ramps are not possible.
Some elevators can also travel horizontally in addition to the usual vertical motion.

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1. ### I Question about Einstein's famous elevator experiment

Hi, In Einstein's famous elevator experiment, someone in the elevator cannot tell if the acceleration they experience is from the gravity of a nearby large mass, or from their own change of velocity under the influence of some external force. But if there is an external force accelerating...
2. ### Pushing a block against the wall of an elevator that is accelerating

Easier case: Elevator is at rest. We need to prevent box from free fall so friction should be bigger than "mg".(And they can be equal) When we push with force F we know that the maximum static friction is ##u_sF##. "mg" should be smaller than ##u_sF## or should be equal to it so the minimum...
3. ### B Elevator Question -- What does a downward acceleration mean?

If an elevator is moving upward, what does a downward acceleration mean? When applying the free body diagram, will the positive direction be upwards since the elevator is moving up?
4. ### Exploring the Average Power of an Elevator: A Physics Perspective

The answer in the book is 400w. It said that ##P_{av}=Fv_{av}cos(F,v)=mgv_{av}cos(F,v)=400##w and F is upward force that is applied by elevator. Should velocity of the elevator be constant? Because it said that we have F=mg.
5. ### Angular acceleration problem for a pulley used to raise an elevator

I tried to multiply 1/8 g (1.22625) by the radius (1.25 m) and got 1.53 rad/s^2. This is actually the linear acceleration of the elevator. How do I get the angular acceleration of the disk? Thanks!
6. ### Student sliding bag along floor in elevator

For this problem, The solution is, However, is the reason why they don't do ##-0.5a_xt^2## because the negative of the acceleration has already taken care of itself? Many thanks!
7. ### Calculating Net Force of 3 Blocks in an Elevator

m1 = 4 kg, m2 = 12 kg, m3 = 8 kg. k = 327 N/m for all three blocks. The elevator accelerates upwards at 3.8 m/s^2. Net force of block one would be equal to force applied by top spring minus weight of system, since top spring is holding all 3 blocks. F1 = 4*3.8= Fs,top - Wsystem = Fs,top -...
8. ### Does an airliner use elevator in a coordinated turn?

So I understand that for an airliner to make a turn, the plane has to use ailerons to roll to one side to shift the lift to create a centripetal acceleration, and because of the drag difference of the two wings, the rudder might also turn to that direction to correct for the adverse yaw. I'd...
9. ### I Light in an accelerated elevator

Elevator (2m height) is accelerate upward, light is at the top pointed toward flor of elevator. Is time t=2m/c to light pass from top to bottom? Bottom moving toward light,so time would be smaller then t=2m/c?
10. ### Elevator falling and bouncing back from a spring

I don't understand the difference between part c and d. After compressing the spring, the elevator bounds back and moves before coming to rest in both cases. What is the difference? Thank you.
11. ### I Calculation of gravitational redshift in an accelerating elevator

When we derive the formula of the redshift by the equivalence principle we imagine a light ray which goes from the bottom to the top of the elevator and which would take a duration t = h/c to make the journey, with h = height of the elevator. I don't understand why t = h/c, because while the ray...
12. ### Questioning the Solution for Elevator vs Rock Problem

Hi everyone I have solutions to this problem, but I am not sure if the premise behind them is correct. I think this is the reasoning behind the solution for question d. - Work out how far the elevator travels in the 7s before the rock is thrown, so 7x2.5 = 17.5 - Work out how far the...
13. ### Work done in elevator problem — is it positive or negative?

Hi! So, I've actually already solved this problem.. for the most part. I have split up the work into two sections, floor 0 to 10, and floor 10 to 15. From floor 0 to 10, I did ## F_{elevator} = w_{pass.} + w_{elev.} ## ## F = (70)(20 (num. of pass.))(9.8) + (800)(9.8) ## ## F_{elev.} = 21560N...
14. ### Work done on a falling elevator by a spring + gravity

I don't understand what I have done wrong in part (c) I have the initial velocity for the second part of the motion and have the final velocity zero and then the net work done is W_mg + W_Fs and the actual answer for x is 2.37m Could I get some help/tips please, thanks in advance. Here is my...
15. ### I Calculating your weight in an elevator

I was watching one of Walter Lewin's lectures, he gave an example of a scale placed at your feet in a moving platform, apparently your weight changes when the moving platform accelerates downward, my question is if my reasoning is correct. I'm wondering why your feet stay in contact with the...
16. ### I Mass of Backpack in Moving Elevator

A backpack is attached to a spring scale which is attached to the ceiling of an elevator. The elevator is moving downwards with an acceleration of 3.8 m/s^2. The scale reads 60 N (Fscale). What is the mass of the backpack? The solution to this problem says that Fscale - w (weight) = Fnet. This...
17. ### I Why don't we "fly up" in an accelerating elevator?

Earlier I was doing a sample problem for class that involved the work done by an elevator, and the problem gave us the normal force experienced by the person in the elevator (to calculate the acceleration of the elevator-person system). I had done this wrong because I had wrongly assumed...
18. ### F = ma for a lift (elevator) carrying passengers

Summary:: What constitutes the 'body' when applying equation of motion? I was solving this problem: 'A woman of mass 60 kg is in a lift of mass 250 kg which is accelerating downwards at 3.2 m-2. Find the tension in the cable of the lift.' when I realized that I'm not sure what constitutes the...
19. ### Calculate the net energy of this system (mass and Slinky in an elevator)

The slinky is designed to fully contract in 1 second. During this one second, the mass is weightless and move up at constant speed of 1m/s. After 1 second the mass gain 1m height in potential energy. Am I missing something?
20. ### What are the forces at play in an elevator cab?

I mentioned answers above in the question.
21. ### Work Done by Elevator Cable in Sample Problem 7-6

As stated, part (a) says that the work done by the gravitational force ##\vec{F_g}## is 59 kJ. If ##W_T## is the work done by the elevator cable during the 12 m fall, then using the work-kinetic energy theorem, \begin{align*} K_f -K_i &= W_g + W_T\\ \frac12m({v_f}^2 - {v_i}^2) &= 59000 + W_T\\...
22. ### A Einstein's Elevator Trajectories: Desloge & Philpott 1987, Hamilton 1978

Hello, Some papers describe the vertical motion of a ray of light or a non-zero mass particle in a uniformly accelerated reference frame in special relativity: Desloge, E. A., & Philpott, R. J. (1987). Uniformly accelerated reference frames in special relativity. American Journal of Physics...
23. ### Elevator Frame Design: Can It Stand Alone?

Hello there, I am wondering, if I were to build an elevator in a building, is it possible if I build the elevator frame (and rails) without using the rail bracket? The weight of the cart plus the contents would be supported by only 4 steel columns fixed to the ground. I know it is a silly...
24. ### Find the power needed to accelerate this elevator downward

An elevator of mass M is accelerating downward with constant acceleration A. Friction force acting on the elevator is constant and given by f (The initial speed of the elevator is zero.). Find the power generated by the engine of the elevator (in terms of M, A, g, f, and time t). For this...
25. ### Engineering Simulating the movement pattern of an elevator using a class D chopper

The question: Here's my attempt: However, I got stuck, I don't know what should be connected to the gate of the switches as the duty cycle changes in each case. Should I insert a pulse generator with 0.5% duty cycle for the 1st case, another pulse generator with a duty cycle > 50% (for...
26. ### Man on an Elevator -- Force Diagrams

I really need help figuring out where to start. I believe that every graph has a normal force pushing up on the person as well ag gravitational force pushing down on them. Where I am getting confused at is how the velocity plays into the scenario and if an acceleration of 9.8 m/s^2 downwards is...
27. ### Mechanics: Elevator Accelerating Downward

The acceleration of the elevator is downwards and therefore negative. The overall acceleration of the man is downward with the the direction of the elevator meaning that ma is negative. The external forces acting on the man are the force of gravity acting downwards (-W=-mg) and the supporting...
28. ### Climbing a ladder in an elevator

I have found the apparent weight of the man in the accelerating elevator My question is about what speed I should use in the formula for the power output P = F ⋅ speed My common sense tells me that the speed I should us is the speed v the man is climbing the ladder , because if the...

30. ### Power To Accelerate 1000kg Elevator Cab Upward

(a) When the cab is carrying its maximum capacity, at what rate must the motor deliver energy to get the cab up to cruising speed? My shot was finding the acceleration, a=1.5/2 = 0.75m/s2 Displacement of elevator Vf2 = vi2 + 2aΔx Δx = 1.5m Force of elevator (Since it accelerates...
31. ### B Forces inside a moving elevator

For some reason this is something I have really hard time wrapping my head around. Suppose you are sitting on a chair inside a completely closed elevator. The elevator might be moving vertically at a completely constant speed, or it might be completely stationary. It is my understanding that...
32. ### Woman standing on a scale in an elevator accelerating downward

For A, I had multiplied 65 and 9.8 since that’s the force of gravity. For B, I again multiplied 65 and 2.5 (that’s what the scale says it reads. *I believe you multiply them for c and d, but I’m not positive for it. C- I think you multiply then subtract D- I think you multiply and I’m not sure...
33. ### Understanding Sign Conventions in Elevator Tension Problems

So the first thing that I did was solve for the acceleration of the elevator, given the velocities and distances given in the question. My question regarding this issue is not so much the procedure needed to solve the question, but rather the sign conventions for the values given and calculated...
34. ### Work done by an electric motor to drive elevator

https://www.physicsforums.com/attachments/250022 For the part (a), set the tension of the string that pulls the elevator be ##T_1## and the tension that pushes the counterweight be ##T_2##. Then we have the following equations: $$T_1−1200g=1200 \cdot 1.5$$ $$1000g−T_2=1000 \cdot (−1.5)$$ where...
35. ### Solving for weight and mass in kg in an elevator

Fn= normal force W=mg W=(65)(9.8)= 637N Fn-637= -(65)(0.2*9.8) Fn= 509.6N I got the weight of the woman in the elevator, but I have trouble finding what the scale reads in kg. I was given the solution which read: a = (g-0.2g)= 0.8g W= 0.8g*509.6N= 52kg. My questions 1. why do I have to...
36. ### I A "space elevator" extended to Neptune's orbit

Summary: Achieving speed of light with Earth's rotation Excuse my ignorance, but I think of dumb things. If you theoretically built a strong, lightweight cable that traversed over 2.5 billion miles attached to the rotating Earth, the tip would be traveling at or greater than the speed of...
37. ### Experimental Determination of “g” using an Elevator

I’m kind of stuck on this one. I don’t see how we can use the acceleration of an elevator to find anything about the value of g. We can of course get the acceleration of the elevator, but it feels like that would be independent of gravitational strength. I feel like we need the mass or the...
38. ### Elevator Question: Calculating displacement from weighing scale readings

EDIT: As per @Orodruin 's suggestion(s), I have edited my problems and equations, sorry for the confusion as I typed this out hasty. So from this question, I understand I have to find the net force for the first 10 seconds and deceleration for 20 seconds. The scale shows the force with which...
39. ### Laws of motion and a projectile thrown from an accelerating elevator car

At the moment of throwing the ball the ball will have a vertical vel of 4 and horizontal of 3 wrt to elevator so as seen from inside the elevator the ball will behave like a projectile where g(eff) = 8 and with time period 1 sec hence range will be the displacement which should be 3 m but ans...
40. ### Olds Elevator vs Traditional Archimedes Screw

This device... ... is purportedly superior to the more traditional Archimedes lift where the screw is rotated and the tube is stationary. The video itself does not explain the comparative physics very thoroughly. From the video itself and from the comments section, three broad types of...
41. ### MHB Estimate k0 for Elevator Probability of 10 Stops

10 people get on an elevator on the first floor of a seven-story building. Each gets off at one of the six higher floor chosen at random. What is the expected number of stops the elevator makes? Generalize the result for a k -store building with k>2: Estimate the value k0 such that the...
42. ### Is the Normal Force in an Elevator Conservative?

Consider a body inside an elevator. When it goes up and down, I believe that normal work (positive on the rise and negative on the descent). My question is: since the total work on the closed path is zero, can we say that the normal force is conservative?
43. ### Calculate elevator acceleration using mass

Homework Statement A man with a mass of 65kg is traveling in an elevator and stands on a set of scales, at a given instant the scales measure his weight to be 72kg, find the acceleration of the equation Homework Equations f=ma w=mg FN =mg+ma[/B] The Attempt at a Solution [/B] I know that...
44. ### What is the power input of a motor pulling up an elevator?

Homework Statement Once under way at a steady speed, the 1100-kg elevator A rises at the rate of 1 story (2.74 m) per second. Determine the power input Pin into the motor unit M if the combined mechanical and electrical efficiency of the system is e = 0.76. Here is a link to the diagram for...
45. ### Space elevator minimum initial speed

Homework Statement In the far future, humans have built a space elevator as a cheap means of access to space. However before that could be done, a few basic principles had to be worked out. . . a) What is the minimum initial speed (in an Earth-centered inertial reference frame) needed for an...
46. ### Einstein's Elevator: Gravity vs Acceleration

In Einstein's thought experiment (if I understand it correctly) a person in a sealed elevator in space accelerating at 9.807 m/s2 would not be able to tell the difference between that and the effect of gravity on Earth. Is there any sort of experiment the person in the elevator could do that...
47. ### How Does Elevator Physics Affect the Work Done by a Cable?

Homework Statement Question from fundamental of physics, Halliday Resnick Walker In Figure below, a ##m=0.250## kg block of cheese lies on the floor of a ##M=900 kg## elevator cab that is being pulled upward by a cable through distance ##d1 =2.40 m## and then through distance ##d2 = 10.5 m##...
48. ### Do Air Molecules in a Sealed Elevator Accelerate Equally When It Speeds Up?

If a sealed elevator moving with a constant velocity in upward direction suddenly starts accelerating upwards with an acceleration "a" ,will all the air molecules inside the elevator also accelerate with the same acceleration?
49. ### Elevator Motion and Bathroom Scale Readings

Homework Statement A physics student . stands on a bathroom scale, calibrated in Newtons, while riding in an elevator. How will the reading on the bathroom scale compare to the normal reading for the following sequence of the elevator's motion? elevator starts to descend; elevator descends at...
50. ### Calculating Elevator Acceleration: Solve for F=ma

Homework Statement A person stands on a bathroom scale in a motionless elevator. When the elevator begins to move, the scale briefly reads 1.05 times the persons regular weight. Calculate the magnitude and direction of the acceleration of the elevator. Homework Equations F=ma The Attempt at a...