What is Push: Definition and 204 Discussions

Push technology, or server push, is a style of Internet-based communication where the request for a given transaction is initiated by the publisher or central server. It is contrasted with pull/get, where the request for the transmission of information is initiated by the receiver or client.
Push services are often based on information preferences expressed in advance. This is called a publish/subscribe model. A client "subscribes" to various information "channels" provided by a server; whenever new content is available on one of those channels, the server pushes that information out to the client.
Push is sometimes emulated with a polling technique, particularly under circumstances where a real push is not possible, such as sites with security policies that require rejection of incoming HTTP/S requests.

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  1. danielng245

    Please help calculate flowrate frm blower to push water down

    How to calculate how much flowrate from blower i can push water pool 2,75m*1,8m down by 1,25m in 1 sec? Note : Blower Pressure 0.03 bar - 0.035 bar There is an empty room above the water pool with dimension of 2.75m*1.8m*1.7m This process happen in a closed chamber...
  2. C

    What Does Equation 5.7 in Introducing Einstein's Relativity Really Mean?

    Hello. I'm going through Ray D'Inverno's "Introducing Einstein's Relativity" and I'm stuck at a certain point and can't move forward. It deals with tensors, I'm stuck at the transformation matrix and the problem is, I can't figure out what the key equation (5.7) actually means. There is a...
  3. M

    Static load Vs Push force on an actuator

    Hello all, I have an actuator to lift a table, with certain amount of wait on it. Since I have mounted the actuator in an angle, I had to analyze the load on the actuator. However, the velocity at which I am lifting the table is bare minimum compared to the load on the table. So I had the...
  4. D

    How hard can you push something given grip strength?

    Hello, I was hoping you could solve an argument. We are wondering how hard you can push something. Let's say I have a piece of wood clamped down on a table and I want to push the piece of wood left or right. If the clamp is pushing down on the piece of wood at 100 pounds, I would need 100...
  5. X

    Why is work negative when we push two opposite particles tog

    The below is what has me confused. It's essentially stating that if we apply a force on a positive charge and push it close to a negative charge, our applied work is negative. Why is this? I am confused about it because W = Fd and both F and d have the same direction. The potential energy U...
  6. G

    How does a magnetic field "push" charges?

    I was under the assumption that a magnetic field acts similar to that of the normal force in mechanics; both affect the path of the object, but do no work. So now suppose that we have a rectangular circuit with the left side in an uniform magnetic field that is pointing towards the computer...
  7. G

    Push Rod Suspension Geometry Question Camber Change Wheels

    Hey, I've spent ages trying to solve what seems to be a pretty simple geometrical problem and I was wondering if anyone could help me solve it/give me some tips. I am trying to model how the suspension of a car behaves as a result of a displacement of the wheels. What the attachment shows is a...
  8. S

    Why two men can't lift a 2 ton car but can push same car

    Hi Guys, I am wondering that what physics involved here. 1. Why two men can't lift 2 ton car at 1 meter height but can push same car up to even 1000 meter. 2. At start car push takes much energy but later it requires less energy to push So weight is same but 2 men can't move car vertically...
  9. evinda

    MHB Exploring Pop & Push: Memory Requirements in C

    Hello! (Smile) I am looking at the algorithms Pop and Push of a stack: void Push(info x, pointer S) pointer P; /* temporary pointer */ P=NewCell(NODE); /* malloc() */ P->data=x; P->next = S; S=P; /* This wouldn't give the right result in C*/ Why doesn't...
  10. L

    Finding minimum push force for a table

    Homework Statement The coefficient of static friction between a static friction and a 20kg table and the floor is 0.29. The coefficient of kinetic friction between the same surfaces is 0.25. How much minimum push force is required to get the table moving? How much push force is required to...
  11. T

    Could a person do this? -- Push a cruise ship by hand

    I was watching a program on the worlds largest cruise ship, the Oasis of the Seas. It displaces 243000 tons. They we're discussing the sophisticated maneuvering systems and I got to thinking. Let's say the ship is docked, within a foot of the dock and untethered. If I sat down with my legs...
  12. A

    Push Forward on a Product Manifold.

    Some words before the question. For two smooth manifolds M and P It is true that T(M\times P)\simeq TM\times TP If I have local coordinates \lambda on M and q on P then (\lambda, q) are local coordinates on M\times P (right?). This means that in these local coordinates the tanget vectors are...
  13. J

    What is the work required to push three protons to form an nucleus?

    Hello there, Imagine that a nucleus consists of three atoms arranged in a equilateral triangle with the length of each side, ##R=2 \rm fm##. Our protons starts infinitely far away. What is the work required to push these protons together in order to overcome the electric force between them? I...
  14. C

    Gas or liquid which can push piston

    Greetings .! This is regarding a lab experiment .I need to find out if we can boil or heat a liquid ,which is connected by with a manometer and a piston .We need to push the piston and also see the reading in the manometer. Which is the ideal liquid or gas , which will not eak or hold on to...
  15. N

    If you push something and it doesn't move does it have energy?

    If you push something and it doesn't move does it have energy? So if I push something to apply a force, that requires energy right, but if the object like a building for example, doesn't move where does the energy go? Another way I was looking at it was if a ball collides with another...
  16. W

    How high can you push water vapor from solarthermal desalination?

    Hi all, Yet another noob question from me... I been thinking of Solarthermal desalination plant lately but I'm surprised that no plan seems to take into account the possibility of letting the vapor rise to a much higher level, thus creating a potential energy source. Is there something...
  17. D

    Force Needed to Push 30 Tonne Rubbish in Steel Container

    Hello members, Can anyone help me with the following. How much force is required to push 30 tonne of rubbish from a enclosed smooth steel container, sitting level with the ground? Rubbish contents (timber, plastic, dirt, food, etc) I was under the impression that the coefficient...
  18. jmex

    Calculating Push Force to Drag Cow Manure: Guide & Tips

    hello folks, If i want to drag(push force) cow manure of suppose 500kg and i took help from google to find out its coefficient of friction which is found is 0.4 to 0.8. So according to F=μN if i am right taking 0.8 coefficient of friction, my push force is 500*0.8? Is there any other...
  19. D

    Can I Push the Moon Instantly?

    Can a push, be faster than light? If I was to hold a stick that stretched out to the moon, and pushed it. Could I push the moon instantly? Seeing as that the stick could defy physics etc and I had enough strength to make an impact on the moon.
  20. D

    Calculating Push & Pull Forces | Andre's Physics Questions

    Hello, I'm new to this forum with little knowledge of physics. Does anyone know how to calculate the force created by pushing and pulling on object (i.e. a car stuck in the snow) versus pushing versus pulling? I.e., which of the three forces is the greatest? My physical experience...
  21. L

    Energy needed to push a volume of water

    Hello! I just found this website and it looks amazing! I'm not a scientist or anything, but I love it (should've studied physics but oh well), so I think it will be fun and useful for me to join this forum. I am trying to solve a situation, where I'd like to know how much energy would be...
  22. B

    Tom and Jerry push on the 3 m diameter merry-go-round

    Tom and Jerry both push on the 3 m diameter merry-go-round shown in the figure attached. (a) If Tom pushes with a force of 40 N and Jerry pushes with a force of 35.2 N, what is the net torque on the merry-go-round? (b) What is the net torque if Jerry reverses the direction by 180 degrees...
  23. M

    Push out solenoid force-distance problem

    I want to purchase a push out solenoid for throwing stuff into air and need help deciding the best one... I want to push 4kg of load into air at 90degress starting from rest to a height of atleast 3 metres. How much force(in Newtons ) would that need ? Also if you could explain the method you...
  24. J

    Force required to push an object a certain distance

    If someone wanted going to push a static object a certain amount of distance how would you calculate the force the person needs to apply to the object? I know you have to take the static force of friction into account so let's say the force of static friction is 10N to get the object moving, I...
  25. V

    What Forces Keep the Book Stable on an Inclined Bookshelf?

    Homework Statement A 0.407 kg book rests at an angle against one side of a bookshelf. The magnitude and direction of the total force exerted on the book by the left side of the bookshelf are given by: Force Left = 2.17 Newtons and θ=59 degrees What must the magnitude and direction of...
  26. B

    Do electrons push each other in a circuit ?

    i have a made a thread a few hours ago with something related to this but i would like to know do electrons push each other in a circuit ? that would explain the constant intensity across a circuit before electrons even reach a resistor . i mean they push each other like some kind of...
  27. A

    Calculating Work to Push a Charge from Infinity

    I have just read a thread here:https://www.physicsforums.com/showthread.php?t=382031 Here is part from the thread. Please see the bold sentence in the quote. In this case, does it mean that my force(push) is larger than the push force from fixed charge. If so, how can I calculate the work that...
  28. W

    How many joules expended for a push up?

    Just wondering if any of you can do the calculation that well approximates the amount of joules expended by a push up.
  29. DiracPool

    Is the push to stop smoking going too far?

    Ok, this a thread about the push, at least in the USA, to stop smoking. I'll start with an abridged history as far as I know it. We have been innundated with cigarettes everywhere we look, such as supermarkets, convenience stores, gas stations, etc. ever since I can remember. And although...
  30. B

    How to calculate force needed to push piston based on crankshaft value

    Homework Statement How do you calculate the force needed to push against a piston based on the mass of the vehicle, the rpm of the crankshaft, radius of crankshaft (same distance as the center of the crankshaft to the attachment point of the connecting rod and the crankshaft), and the length...
  31. Q

    Will a push out window or half slide window cool down a room faster?

    If you have a push out window the whole area is open but much of the wind is blocked depending on the angle. With a slide window you often have half the open area but you can get direct wind over 180 degree angle. Which one will cool the room down faster under which circumstance? If there is...
  32. N

    Calculating Push Time for a Moving Crate

    Homework Statement A crate is initially at rest on a rough, horizontal floor. The crate moves in a straight line as it is pushed resulting in the crate speeding up at a constant rate of 2.85 m/s2. After a while, the crate is no longer being pushed and the crate slows down at a constant rate...
  33. reddvoid

    Is PUSH A Instruction Valid in 8085?

    Is PUSH A Instruction Valid in 8085 I get this doubt because PUSH and POP always acts on register pairs but only register pairs available in 8085 are BC DE HL there is no register to pair with A so ?
  34. D

    Is it possible to push Earth down more than you weigh?

    Here's a question that I'm pretty sure I know the answer to, but I was talking with a friend earlier and it just made me second guess... So let's say You are a bodybuilder. One day you decide to get on your knees (in a stationary position) and try and push the Earth down. Is the amount of...
  35. reddvoid

    About PUSH and POP in microprocessor/controller

    Does PUSH operation moves or copies data from register to top of stack ; I mean, what happens to the contents of the register from which the data is pushed ?
  36. C

    Force to push mass down inclined plane

    Homework Statement The angle of the ramp is 30 degrees. The mass is 40 kg. What force must be applied to keep the mass sliding down the ramp at constant velocity. The ramp is frictionless* Homework Equations I have missed the past few lessons in class, so I'm not sure. I do have a bunch of...
  37. A

    Does force normal change when you push an object at an angle?

    Homework Statement You exert a force of 131 N [30° below horizontal] onto a 12.6 kg lawn mower, What is the force of gravity and normal force on the lawn mower?Homework Equations Fg= m × g FA (y component) = Sin30° × FAThe Attempt at a Solution The force of gravity is equal to the force of...
  38. P

    How do I figure out how much water force is needed to push how much weight?

    Hi guys. I'm trying to figure out how much water force is needed to push an object roughly 19 times heavier then itself. I think water is roughly 2lbs in weight to every 32 fluid ounces. any one think they can give me a hand?
  39. A

    Push a crate up a frictionless incline

    Homework Statement To push a 29 kg crate up a frictionless incline, angled at 39° to the horizontal, a worker exerts a force of 321.9 N, parallel to the incline. As the crate slides 1.50 m, how much work is done on the crate by the worker's applied force? How much work is done on the...
  40. V

    Vertical Centripetal Force to push an object

    I have this device, It has 3 masses 30 grams each (Red ones) the other masses are not considered. The masses are spinning at 600 rpm at that velocity this will reach maximun radius. The maximun radius the masses and reach due to the centripetal force is 15cm. Can this device push a 3kg mass at...
  41. J

    Using length contraction to push a bomb trigger

    Inspired by Aziza's question i came up with a similar, seemingly puzzling question. Imagine a space-platform with a big cylinder on it. The cylinder has a hole drilled in, with a bomb-button at the end of the hole, which would trigger a bomb destroying the whole galaxy. A terrorist is on that...
  42. P

    If you push on a crate with a force of 100 N and it slides at constant velocity, how

    If you push on a crate with a force of 100 N and it slides at constant velocity, how much is the friction acting on the crate? Consider a crate being pushed horizontally across a factory floor. If it moves at a steady speed in a straight - line path, it is in dynamic equilibrium. This tells...
  43. R

    Can you use magnets to push other magnets unlimited amount of times?

    As I was bored at the lesson, I did some thinking of my own and magnets always fascinated me, still kinda like black magic. Anyway, i was thinking abou creating this: http://img201.imageshack.us/img201/7476/prepetummobile.jpg I created this in paint as fast as possible so it's not super...
  44. H

    Find force to push block up incline with static and kinetic friction in certain time

    pHomework Statement A 5.03 box sits at rest at the bottom of a ramp that is 8.76 long and that is inclined at 30.0 above the horizontal. The coefficient of kinetic friction is 0.40, and the coefficient of static friction is 0.50. What constant force , applied parallel to the surface of the...
  45. A

    Force required to push wheel (not torque)

    Homework Statement How much force is required to push a wheel of radius 50 mm and moment of inertia 3.21*10^-4 kgm^2 to 20 mph in 5 seconds? The wheel has a mass of 0.29 kg. The wheel is to be pushed straight and level at its axel 90 degrees to the horizontal. Homework Equations T =...
  46. T

    Force to push object up ramp

    Homework Statement In the design of a supermarket, there are to be several ramps connecting different parts of the store. Customers will have to push grocery carts up the ramps and it can't be too difficult. An engineer has done a survey and found that no one complains if the force required is...
  47. Z

    What is the required force to push a 5.00-kg box up a 30° incline in 4.00s?

    Homework Statement A 5.00-kg box sits at rest at the bottom of a ramp that is 8.00m long and that is inclined at 30.0° above the horizontal. The coefficient of kinetic friction is μk = 0.40, and the coefficient of static friction is μs = 0.50. What constant force F, applied parallel to the...
  48. C

    Why Does a Car Move at Constant Velocity Despite Equal Opposing Forces?

    I was wondering, if the force that causes a car to move in one direction is matched by the drag force opposing in the other direction, why does the car move at a constant velocity rather than moving at zero velocity. I thought that when one force opposes the other equally, there is no net...
  49. A

    When I push a an object, why does it move?

    A discussion my maths teacher brought up today arguing that the Newton's Third Law pair of pushing on the table and the table pushing against the person should cancel each other out. So there should be no resultant force and it should not move. I argued it was to do with F=ma so if the...
  50. K

    How much lb could an average person push?

    e.g. pushing a door with x-lbs of resistance, assuming a person is exerting force perpendicular to the door, 36" from hinge. What is that x-lbs (max) an average adult could pushing with ease? Thanks
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