What is Lift: Definition and 613 Discussions

A surface lift is a means of cable transport for snow sports in which skiers and snowboarders remain on the ground as they are pulled uphill. While they were once prevalent, they have been overtaken in popularity by higher-capacity and higher-comfort aerial lifts, such as chairlifts and gondola lifts. Today, surface lifts are most often found on beginner slopes, small ski areas, and peripheral slopes. They are also often utilized to access glacier ski slopes because their supports can be anchored in glacier ice due to the lower forces and realigned due to glacier movement.
Surface lifts have some disadvantages compared to aerial lifts: they require more passenger skill and may be difficult for some beginners and children; sometimes they lack a suitable route back to the piste; the snow surface must be continuous; they can get in the way of skiable terrain; they are relatively slow in speed and have lower capacity.
Surface lifts have some advantages over aerial lifts: they can be exited before the lift reaches the top, they can often continue operating in wind conditions too strong for a chairlift; they require less maintenance and are much less expensive to install and operate.

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  1. L

    How much suction required to lift?

    Hi - am looking for some data points on how much suction is required to lift an object at different weights and volumes. Especially interested in any data relative to displacing an object caught in the throat if you are choking. Appreciate any help!
  2. G

    Fluid mechanics calculating force needed to lift submerged disc

    Homework Statement The problem: There is an illustration and the question is to find the force F to lift a concrete block gate if the the concrete weighs 160 lb/ft3. The block is 3' in diameter and 1' thick. It is in a tank of fresh water 15 ft down. the specific weight of the fresh water...
  3. M

    Lift design -no electricity supply?

    Elevator design -no electricity supply? I hope someone can help me. I'm designing a building for uni that requires several lifts (elevators) which transfer bicycles and pallets vertically. My tutor suggested to look at energy efficient lifts. He mentioned that he had seen a lift, which...
  4. Z

    Pascals principle and hydraulic lift

    says that the pressure is distributed evenly around a fluid. What I'm having a hard time understanding is the hydraulic lift, so I thought I would think of a simple system that could represent a fluid and then use that for intuition. Regrettably I did not get the same conclusions with that...
  5. G

    Possible to prove difference between Scissor Lift vs. Straight Lift?

    I've tried to come up with a simple model for scissor lifts and came to the conclusion that the force applied to the centre, by the screw must be the (payload + top arms)/tanθ I set payload + top arms = 981 N I then found the average value of the function by integrating from 15 to 90° and...
  6. B

    Max weight that anyone can lift using over head pulley.

    Can a man whose weight is 50KG (but powerful arms) lift another man with 70 KG weight using an overhead pulley. I guess no since the light man is not clamped to the groud, his arm strength will not bear any significance and he can lift only the wieght(on other side of the pulley) equal to his...
  7. V

    Is there is any change in time period if it is done inside accelerating lift?

    Homework Statement Q1> there is a cube like jar of water kept at the surface of a lift which is moving with an acceleration of a in upward direction. jar is filled with water. There is a cubical block of wood floating on it's surface. It is slightly pressed and released. find the time period...
  8. S

    Calculating the maximum load a lorry can lift

    Please help with this query to find how much load a dumper truck can lift without it becoming unstable and toppling. Homework Statement A lorry has a volume of 42 cubic metres and can hold 78,000kg sand. The overall length of the vehicle is 9.5m with a pivot 1.2m from an end. The bed...
  9. K

    What is the total lift for a fixed wing plane and helicopter?

    I came to know that Fixed wing as well as propeller lift equations are same [Am I right]? Anyways I have question. What's total lift for fixed wing plane with Wing length of 4 m, 1 m width, Angle of attack = 16 degree, and Wind/plane speed of 6 m/s? Secondly, what's total lift for...
  10. S

    Calculating Forces in a Moving Lift

    Homework Statement (in these questions we were told that g+ 10ms/s i know its not strictly true g should be 9.81 but our teacher told us to do this) 2. A 35 kg block rests on the floor of a lift. Find the force between the floor and the block if the lift (i) accelerates upwards at 4...
  11. G

    Why does the front end of the car lift up when accelerating forward?

    Can anyone explain it to me? Why does the front end of the car lift forward when it is accelerating forward? Is there a torque that is causing this lift?
  12. K

    Scissor Lift beam calculations

    I am trying to understand how calculate the forces in the beams or atleast how they relate to each other. There is a pin at the top right its just hidden as it is a wheel behind the rail. I am confused at the pin where the cylinder connects on how the load would be transferred to the lower parts...
  13. L

    Calculating Force Needed to Lift Lid in Denver

    Homework Statement A lid is put on a box that is 14 cm long, 12 cm wide, and 8.0 cm tall and the box is then evacuated until its inner pressure is 9.0 104 Pa. How much force is required to lift the lid in Denver on a day when the atmospheric pressure is 67.5 kPa (2/3 the value at sea...
  14. L

    Lift relative velocity problem.

    Homework Statement motor is mounted on top of lift. a)if p moves by y, what is the displacement of Pt A? Prove that Vp=-3Va. b)If motor unwidns cable at const rate 2m/s, what is vel of cable wrt lift. Prove vel of lift is 0.5m/s Homework Equations The Attempt at a Solution I...
  15. S

    Hydraulic scissor lift using syringes

    I m making a hydraulic lift using syringes (piston and cylinder mechanism). can anyone suggest the combination of syringes for maximum displacement. will the scissor lift work properly?
  16. P

    Calculation of lift and thrust

    I need some information and guidance on how to calculate net lift and thrust produced by wings of an MAV(micro air vehicle) which are flapping and active pitching. I know only about one method which is the Blade Element Analysis, but it is just an approximation and doesn't accounts for...
  17. M

    Energy required to lift 1 pound 3 inches at 70 MPH

    Hi, I have a few energy questions and I'm hoping they are welcomed at this forum. I'm dealing with the idea of reducing "unsprung weight" on motorcycles. This is the weight of items below the suspension, i.e. the wheel, tire, brake discs etc. My first foray into this was back in the...
  18. C

    Exploring the Possibility of a Vacuum-based Buoyancy System for Atmospheric Lift

    Hi, first time posting here. I was watching a show about hydrogen/helium balloons and it got me thinking about buoyancy in atmospheric gasses (nitrogen) and what might work better than the common gasses and I considered that since the goal of a balloon is to reduce the internal mass relative to...
  19. K

    Finding Happiness Through Stories: Non-Self Help Books to Lift Your Spirits

    Hi all. I would really like to get better at appreciating things in my life, and being more comfortable and confident talking to others. It would sound like 'self help' book territory, but I hate self-help books. I just don't do well with them. My friend Jesse told me about a book he was...
  20. T

    Understanding Lift: Force on Wing & Fluid Reaction

    This is a quote I read and I am having problems understanding it: "Lift is produced by the changing direction of the flow around a wing. The change of direction results in a change of velocity (even if there is no speed change, just as seen in uniform circular motion), which is an...
  21. B

    Pressure required to lift a weight

    Assume all dims in millimeters and kilos and I am working on a hydraulic set up I have a cylinder Ø200mm diameter x 400 high, it has a hole in the middle Ø10mm going into a capped Ø10mm pipe. The cylinder is filled with water up to 300mm high. There is a bouyant weight that floats on top of the...
  22. C

    Time it takes to lift a sofa with power

    Homework Statement Your sofa won't fit through the door of your new sixth-floor apartment, so you use a 1.18 kW motor to lift the 84.7 kg sofa 18.8 m from the street. How much time does the lift take? Homework Equations KE_i+PE_i=KE_f+PE_f (If forces are conserved? I'm not sure if...
  23. G

    How can I lift more than my weight?

    There is a tricep machine which is basically a pulley, with some rope connected to a stack of weights and a bar for you to push down on using your triceps on the other end of the rope. How is it possible that if I'm 140 pounds, I can lift like 180 or more on that machine? If I want to want...
  24. A

    Fluid Mechanics; Lift Force on a Roof; Bernoulli's Equation

    Homework Statement I need to find the net force acting on a flat squared roof with area A while the wind is blowing outside at some velocity, v_1. Homework Equations Bernoulli's Equation: P_1+\frac{1}{2}\rho v_1^2+\rho gy_1= P_2+\frac{1}{2}\rho v_2^2+\rho gy_2 The Attempt at a...
  25. M

    Force required to lift a bar pivoting on one end

    Homework Statement This is actually for a "hobby" project, not at all academically related, but I'm posting it here because I know it's very elementary. I'm just having more trouble with it than I should but it's been five years since my last Physics class so I felt like I partly have an...
  26. T

    Lift, Drag, Normal, and Axial Forces on a Flat Plate

    Homework Statement Consider an infinite thin flat plate with a 1m chord at an angle of attack of 10 degrees in a super sonic flow. Describe the angle theta between the Lift and Normal Force, is it the same as the Drag and Axial? Homework Equations L=Ncos(a)-Asin(a) D=Nsin(a)+Acos(a)...
  27. P

    Lift Problem involving forces, acceleration and speed

    Homework Statement A Lift in a mine shaft takes exactly one minute to descend 500m. It starts from rest , accelerates uniformly for 12.5 seconds to a constant speed which it maintains for some time and then decelerates uniformly to stop at the bottom of the shaft. The mass of the lift is 5...
  28. C

    How much lbf is required to lift 300lbs

    15inches above ground ; hovering, stabilizing system is assumed in the system.
  29. Y

    Aerodynamics: Exploring Lift and its Formula

    I'm currently doing the IB (equivalent to A levels) and we have to do a research on a subject and i took aerodynamics, specifically lift and can someone explain to me how the lift formula(F= Lift coeffecient x area x air density x velocity squared ) is found ? Thank you very much
  30. A

    Understanding Lift Generated by Rowing Blades

    Here is my question: To my understanding aerofoils on an airplane air flow moves (horizontally) in the same direction as the motion of the aircraft; the aero foil then creates a pressure difference and an unbalanced force and lift is generated. Rowing blade manufacturers...
  31. B

    Ballistic Re-entry and the effects of lift

    Hey guys, I understand that 'ballistic re-entry' is usually used in the context of drag only with 0 lift, but if I were to look into the effects of lift how would I go about resolving the forces acting on a body at each instant to determine the instantaneous body acceleration ? My initial...
  32. F

    Is there a more accurate way to calculate lift force in aerodynamics?

    Hi, I'm right now coursing IB (equivalent to A-levels) and one of the compulsory essays we must do is called Extended Essay. It's an essay you do on a topic you choose. I choose aerodynamics. Created a "wind tunnel" out of plastic and made it rigid with hard plastic pieces which were partially...
  33. S

    Calculating Temperature Needed for Hot Air Balloon Lift

    Homework Statement A man wants to go on a hot air balloon trip, and wants to build a balloon with a capacity of 10,000 m^3. The envelope and the balloon have a combined mass of 250 kg. His luggage would be 800 kg. Assume that the ambient air is at a temperature of 20 degrees Celsius. What...
  34. H

    Calculating helicopter lift

    Homework Statement I've been trying to find a simple equation for calculating the lift (or thrust) of a RC helicopter and I've found a few that are different. Homework Equations 1) Lift = circular area swept by rotor blades \times density of air \times velocity of air exiting disk \times...
  35. D

    The Lift Question / reactive force on an object in a moving lift

    Homework Statement A mass of 80 kg rests on the floor of a lift. (Take g = 10ms-2). Calculate: (a) the reaction force exerted on the object by the floor, when the lift is travelling at a steady speed of 2 ms-1 downwards. (b) the reactive force exerted on the object by the floor of the...
  36. E

    Pascal's Law - pressure inside the liquid vs. force needed to lift the liquid

    I'm going to steal a picture that was used in a different thread in this forum. [PLAIN]http://img821.imageshack.us/img821/7469/75687957.jpg (both containers are open at the top, and both contain water) I watched an MIT video of professor Walter Lewin, who used these very same...
  37. J

    Rocket Propulsive efficiency at lift off

    According to Wikipedia: http://en.wikipedia.org/wiki/Propulsive_efficiency the propulsive efficiency of a rocket is at its peak when the rocket is traveling at the same speed as it is ejecting its exhaust. I understand that, but the graph (and equation) on that Wikipedia page (and elsewhere on...
  38. P

    Calculating the Height of Keystone's Ski Lift

    Homework Statement The gondola ski lift at Keystone is 2830 m long. On average, the ski lift rises 14.6 above the horizontal. How high is the top of the ski lift relative to the house?Homework Equations The Attempt at a Solution Drew the picture, did 2830cos(14.6) but don't know what to do next.
  39. F

    Calculating Force Needed to Lift a Rock with a Crowbar

    What equation is used to solve a problem similar to the one below? What force must be applied to the end of a 2.0 meter long crowbar in order to lift a 500 Newton rock if the fulcrum of the bar is .5 meters from the rock? Thanks.
  40. Femme_physics

    Does lift force decrease as speed decreases?

    Or, to be more blunt, does "lift" force even exists in statics? I was rather surprised that our teacher told us that lift force is just as strong as the normal force in statics of an object against ground. It made me wonder just how strong is it. Does lift force decrease when speed decrease...
  41. T

    Calculate the power of a the lift motor

    Please help : Calculate the power of a the lift motor,when is lift on a distance on a building site lift 400kg of brick50m to the top of a buiding in 24 seconds Ans ? Regards. taomay
  42. F

    Supersonic Flight: Lift & Pressure Differences

    Supersonic Lift? Lift appears to be from the angle of attack, due to the deflection of flow-stream in supersonic flight but then in subsonic flight the pressure difference causes lift. So what is going on here that i am missing? Why such a change? Its starting to confuse me.
  43. F

    Generating lift at supersonic speeds

    Im having some trouble understanding how lift is generated at supersonic speed as apposed to subsonic speed. Viscous effects at high speed are greatly reduced and a normal airfoil from subsonic flight is not suitable for such applications. I have had a good read on wiki and other sites but i...
  44. M

    Motor torque calculation for lift having chain drive

    i want to know how to calcuate Starting and running for motor in 2 post lift for lifting 3.0T. Actually i have 2 columns having trapezoidal screw rod and nut in each side. One column is getting drive by motor through pulley belt mechanism. Another shaft is getting driven by chain at the...
  45. R

    Calculating Pulley Ratios for Scissors Lift

    Homework Statement Hi, I am having a problem with calculating the proper sizes for a pulley.The pulleys are turning threaded bars and I want them to turn at different speeds. They are connected via a Belt. There are three pulleys arranged in a triangle. One is the driver pulley(Ø31mm) which I...
  46. A

    Effort Required to lift a load using third order lever

    Homework Statement Calculate the effort required to lift a load of 1962N using a third order lever with load 5m distance from effot and fulcrum 1m distance from effort. Homework Equations i used the following, large distance x small effort = small distance x large effort The...
  47. K

    Single Rotor Versus Coaxial Rotor Lift

    I'm having a tiny debate with someone over whether a 2nd coaxial rotor generates additional lift for a helicopter by itself or the helicopter has additional lift only due to the elimination of the tail rotor so 100% power goes to generating lift? My theory is that it does not generate...
  48. T

    Why does a NACA 643-418 airfoil have a flat region in its lift curve?

    I have plotted a lift curve of a NACA 643-418 airfoil section which has a flat region in the lift curve approximately from 11 degrees to 16 degrees. Beyond 16 degrees it completely stalls. Can some explain to me the reason behind this flat region in the lift curve. The experiment was a force...
  49. J

    How Does Side-Slip Affect Lift Calculation in Flight Simulations?

    I'm writing a flight sim for use in Cinema 4D, an animation package that has a built-in physics engine. It's not supposed to be totally realistic, and I've got most things working fairly well. But one thing I don't understand is how to calculate lift correctly when the relative wind isn't coming...
  50. F

    Could a projectile shooting downward at near c lift 300lbs?

    If a 1 pound projectile was shot out of a stationary, non-fixed object (downward) near the speed of light (on earth) would it lift the object if it were 300 pounds? If so, how far? My friend and I were arguing a hypothetical similar to this.
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