Mechanical Engineering

friction opposes the mechanical advantage of a simple machine.

for example, if you had a inclined plane that gave you an advantage of 3:1 (3 times longer then it is high) the frictional force cause by an object being pushed up the ramp would be in the direction opposite to the direction of motion equal to u*N (mu times the normal force of the object)

so for a 10 kg object being pushed up the ramp, under normal gravity = 9.81 N and a coefficent of friction = .3, the frictional force would be equal to 3 N.

if you were pushing the object on flat ground with a force of 15N, you would actually need 18 N to maintain the same speed of having no friction

appling this to the ramp, if 15N is needed to push on flat ground, only 5 N would be needed to push the object up a 0 friction ramp, and 8 N would be needed to push it up a ramp with friction to maintain the same speed.

this is true for all simple machines, and it only depends on where the friction is being created, weather it be friction between a screw and wood, a rope and the pulley, or the fulcrum and a lever

the difference between frriction bearing and antifriction bearing kya jan ke karega

maal pata dateing ja or as kar......... bye...........

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It is a recurring theme in science fiction that as computers increase in power and sophistication, they may one day reach a point where they decide they can do better without us, and condemn us to lives suspended in racked pods with our brains plugged into a vast virtual world, or alternatively send increasingly resourceful and indestructable robots to hunt us down in our bunkers, while above ground survivors fight a desperate war for survival amidst the wreckage of civilisation.If you find this vision of the future alarming, take heart in this SQL query, which was generated by a machine. Not, perhaps, a Cyberdyne Systems T-800 or the Matrix Mainframe, but something called OLAP API. We don't know what that is either, but we can tell you that if any robot descended from it ever attempts to enslave humanity using a virtual world and an unfeasible pod system, rest assured that you will have time to get out of its way.

Yes. Grade 8.8 refers to a standard (ISO 898-1) which defines the tensile strength (around 55 tons/square inch).

There are many bathroom scales nowadays that are claiming to be accurate. Some of these bathroom scales have gone digital. One way to check that your bathroom scale is giving you accurate results is to calibrate it so that you will know that your bathroom scale is definitely accurate.

Try weighing something that you know the exact weight of. For example, weigh 10kilos of sugar or flour on the bathroom scale and check if it gives the exact result of 10kilos. If it does, then it is definitely accurate. But it if it gives you far off result, then the bathroom scale isn't worth it.

275

The modulus of elasticity , E, relates tensile stress to tensile strain

The modulus of rigidity, G, relates shear stress to shear strain

The bulk modulus, K, relates compressive stress to volume strain

The three are related using u, poisson ratio of material, that varies generally from 0 to 0.5

E = 9K/ (1 + 3K/G)

G = E/2(1+u)

G = 3(1-2u)K/2(1+u)

No, with decrease in temperature it increases a bit, but not much; perhaps by 3% or so

conventional milling is the preferred method on the machines we use. This means that the depth of cut is applied when the tool is nearer to you with the work piece furthest away, with the tool turning clock wise this means that the tool is working against the material when the work is wound towards you in say the y axis, climb milling is normally used in CNC conditions, but if attempted on a manual mill there is a tendency for the work to be 'pulled through' by the motion of the cutter if the depth of cut is applied with the work closest to you and the tool furthest away

Astm 50

1. hydraulic system are self lubricated
2. they don't produce much noise when compared to pneumatic system

make sure it's full of oil

sudden load differ from impact load by the velocity of loading

Well one of the main disadvantages of blow moulding is the amount of cheese that gathers up around the head when blowing

The various uses of carbon steel depend on the amount of carbon added to the alloy; for instance, carbon steel with the lowest amount of carbon is called wrought iron and is used for things like fencing. Medium-carbon steel, also called mild steel, is the type of steel that is used for structural purposes in buildings and bridges. High-carbon steel is used for springs and steel wires, while ultra-high carbon steel is called cast iron and is often used to make pots.

dean

it's a mechanical advantage of 1 (meaning no mechanical advantage). This is because no matter how much easier it is to spin a the wheel rather than the axle, its a longer distance of effort force and vice versa.

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True, but that is not what mechanical advantage is! Mechanical advantage IS the trade off between the force required and the distance travelled.

You can find the ideal mechanical advantage of a wheel and axle by dividing the radius of the wheel by the radius of the axle.

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Better. But I think it could be either of the two reciprocal ratios of the radii,

depending on whether the wheel/axle is being used in a 2nd class or 3rd class

lever configuration ... i.e., are you cranking the wheel in order to turn the axle, as

in a winch, or spinning the axle in order to turn the wheel, as in a motor-vehicle ?

The process of molding is shaping liquid or pliable raw material using a rigid frame called a mold or matrix.[1] This itself may have been made using a pattern or model of the final object.

Because the fuel is ignited by a spark plug rather than by compression as is the case with a diesel.

Poor tip preparation, and poor alignment of electrodes, excessive current and hold time will all contribute to burrs,

Massive ballast tanks can be filled with water or air, changing the weight and buoyancy of a sub.

Once dived a sub can use hydroplanes to angle it towards the surface and use propulsion to drive to the surface.