Lift Definition and 593 Threads

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...

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...

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...

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...

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...

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...

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?

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...

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...

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...

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?

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...

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...

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...

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...

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...

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...

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...

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...

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...

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...

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...

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

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

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...

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...

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...

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...

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...

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...

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...

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...

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.

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.

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...

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[FONT="Arial Black"]

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.

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...

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...

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...

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...

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...

[SIZE="2"]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...

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...

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.

I have done a lab experiment, to determine the coefficient of lift for an aerofoil, keeping the angle of attack constant. The equation I have used is Lift= (1/2) v times v times A times ρ times Coefficient of lLift v= Velocity of air ρ=air density A= planform area to give...

Homework Statement How much work must be done by a rocket engine to lift a 1000kg payload from rest on the Earth's surface to a circular orbit of radius 2Re (2 times the radius of the earth)? Homework Equations Eg = -GmM/r Ek = GmM/2r The Attempt at a Solution I know ΔE = W I...

Hi, One cubic foot of air will lift approx 64 lbs in water (basically). So if you start at a xxx depth with a balloon that is one cf, as it rises and expands the lift capability increases, right? What if the container was an aluminum sphere. Actually, say you have 2 same size spheres, both...

Homework Statement Hi there, In my experiment I have a disc which needs to be pitched and rolled about it's centre. The disk is mounted by three verticle "pistons" one every 120degrees. I need to convert a tilt in the x-direction \theta_x and a tilt in the y-direction \theta_y to how much each...

Consider a proposed airplane design shape in a wind tunnel. The forces and moments are measured at the proposed center of gravity location. At zero angle of attack, pitching moment is zero and lift is 10N. At 5 degrees angle of attack, pitching moment is -5Nm and lift is 60N. The chord of the...