I think your question could be rephrased as:
"When viscous friction increases, why does currentdecrease?". Though the latter is not directly dependent on the former, or vice versa, in most motors this is the case. To understand exactly why this happens we need to look into the constructional features of a motor.
All motors have a rotor (the spinning part) and a stator (the stationary part). In linear motors the part the slides along can be thought of as the 'rotor', and the non-moving base, as the 'stator'. The motor spins by causing like poles on the stator and rotor to oppose each other (different motors - AC, DC, brushless - do this in different ways). Read up about this on Wikipedia, HowStuffWorks, or just Google around. For maximum efficiency it is desirable to build the rotor and stator in such a way that there is very little space between the two. This allows a high degree of magnetic flux linkage/concentration between the rotor and stator. Between the rotor and stator is a small air gap. Air, like all fluids, has viscosity (a sort of 'stickyness', if you will). Viscous force appears between two sliding objects which have a liquid in between them. The closer the sliding surfaces, the greater is the viscous force. Viscous force also depends on the area of the surfaces, their relative velocity, and the liquid's properties. For a detailed derivation please refer to any text on fluid dynamics.
Another important motor characteristic is back EMF (BEMF), which is induced in motor coils due to magnetic interaction. The faster a rotor spins, the greater the magnitude od back EMF. Back EMF, as its name suggests, has a polarity opposite to the applied (battery/power source) EMF. It is the back EMF which causes a reduction in motor current, since it partially cancels out the applied EMF : (Applied EMF-Back EMF)=(Effective EMF). Since the coils in the motor have unchanging resistance, a lower apparent EMF imples lower current.
Now let us link these two phenomena:
low speed-->low BEMF-->high current
also;
low speed-->low viscous friction
but:
higher speed-->higher BEMF-->lower current
and:
higher speed-->higher viscous friction
I hope this clears things up.
Rohit de Sa,
Engineer,
That all depends on how viscous the magma (though out of the earth it's called lava) is. More viscous, the bigger and higher it gets. The less viscous, the less violent the explosion can and will be.
The resistance of a liquid to flowing is its viscosity.Viscosity is a property arising from friction between neighboring particles in a fluid that are moving at different velocities. In liquids, it could be considered the "thickness". For example, maple syrup has a higher viscosity than water.
When a liquid is heated, it will generally become less viscous.
Not really. It has a less sweeter taste and is more viscous than "normal" milk is. It's nothing like vanilla milk shakes, you might say it's the opposite of that.
A substance that is sticky, such as honey, or clue. Something that is viscous. Here's a good one. Did you ever pick your nose and the boogie wouldn't come off your finger and you had to keep trying to flick it off? Well, that boogie of yours was tenacious....lol
oil in a car's engine reduces viscous friction and wear
This is known as viscous property
Increase
viscous drag- the same as swimming or diving into a pool.
F. Leprince has written: 'Skin friction determination by LDV measurements in a viscous sublayer' -- subject(s): Turbulent boundary layer, Skin friction (Aerodynamics), Laser Doppler velocimeter 'Skin friction determination by LDV measurements in a viscous sublayer - analysis of systematic errors' -- subject(s): Velocity distribution, Skin friction
Temperature measures the speed of random thermal motion on the atomic and molecular level. When sub-microscopic particles are moving faster, the liquid as a whole will be more fluid and less viscous.
Viscous force. This is the frictional force between layers in relative motion
An autoacceleration is a local increase in the rate of polymerization of a viscous monomer.
any thing that has atoms-the smallest things in nature, causes friction.
There is a thick liquid produced in the joint spaces to cushion and reduce friction. This viscous fluid is called synovial fluid.
Simply by reducing friction and dispersing heat.
The resistive forces of each of those types of friction except for fluid friction depend on both the normal force (exerted on the object by the surface that it's on) and the friction coefficient that corresponds to that type of friction. So naturally we'd increase the force of friction by increasing either or both of those factors. The friction coefficent can be increased by making the surfaces "rougher" so that more of the energy is lost by being turned into heat and/or sound. We can also increase the normal force to increase the force of friction. The most straightforward way is to make the object heavier so that the supporting surface pushes harder against the object, increasing the force of friction. It's important to know that the the normal force decreases when the surface becomes increasingly slanted. For example, an object dropped against a wall is not being held up by the surface at all so there's no normal force. So we can increase the force of friction by making sure that the surface is completely parallel to the ground. That way, the surface is supporting the entire force due to gravity acting on the object. We can also be extreme by changing the "apparent weight" of the object. If the object is on a surface that's accelerating upwards (like an elevator), the force of friction will be higher than normal because the surface will be pushing even harder against the object. For each of the individual friction types, there are some differences. Sliding and static friction are similar to each other. On the other hand, rolling friction often depends on internal friction in the wheel bearings. That's why bearings often use balls to minimize contact area and are well-lubricated. Fluid friction increases with velocity and depends on how viscous the fluid is. The exact relationship between velocity and drag depends a lot on the geometry and speed of the object.