is it always necessary that the friction coefficient be less than 1?
462841
When the calculations were set up for determining coefficient of friction 1 was set as the upper limit. There can be no coefficient larger than 1. Highly smooth surfaces of the same shape (for example, two rectangular blocks) are in almost perfect contact with each other so that almost every molecule of one is in direct contact with every molecule of the other (that's a bit of an exaggeration unless the surfaces are micropolished, but it will serve). The extremely large surface area in contact produces enormous frictional resistance to sliding movement. It helps to understand this if you can make the distinction between smooth and slick. Think for example about trying to slide one heavy glass plate over another without any lubrication between them. They "stick" to each other like glue.
74421
centripetal force is mv^2/r.\nso it comes around 1,777,777.778 N\n\nI need one more parameter that is coeff of friction.\nif that is available u can use\n\nv(max)= sqrt [(rg (u + tan o)/(1 - u * tan o) ]\n\nassuming frictionless\n\nV= sqrt (rg tan o)\nso \no = 66.2 degrees if g=9.8\nand 65.7 degrees if g= 10.
32662
actually the limiting friction is greater than kinetic friction.  it takes more force to overcome the forces of the limiting friction(start the object moving) then it does to overcome kinetic friction(keep the object moving). this makes sense logically, once the object is sliding, it's easier to keep it sliding then it is to start it moving in the first place...
918757
because the moistness causes friction
542734
Meaning moving continually with no additional force needed to overcome frictional or other energy losses.\n\nNo.  It violates the laws of thermodynamics for some process to occur without an energy loss.  If you don't add energy to a system, eventually it will run out of energy.
609002
It doesn't actually come in contact with anything to cause friction.  When a "machine" makes sound, it is made from the moving parts as they hit or rub against one another.  Since a moving pendulum is relying on gravity and its own weight for the arc movements, it doesn't have anything to rub against.
151119
well it could...but not as much because there is less friction.
44667
You have a contradiction in your statement.  Static friction implies no movement but velocity is movement.  \n\nIf you mean the velocity of an object in dynamic equilibrium has a result of a frictional force (kinetic though) like sliding a block across the floor then you have to know the amount of work put into the system.  Then use work-kinetic energy theorem.
834102
1)  I'm not entirely sure.  It may just be the preference of that publisher, or just that the quantities being compared were not measured more accurately than to two places.\n\n2)  The coeffecient of friction is basically a measure of how well two surfaces slide against one another.  Pressing down simply increases the force, it does not necessarily change the structure of the surfaces in contact.\n\n3)  The coefficient of friction has no units because it is a ratio.  If you were to write out the units being compared in a fraction, say 2 Newtons / 4 Newtons, the units would cancel out when divided.
118752
The fricional force between an object and a surface is dependent on two things,\nthe coefficient of friction between the two surfaces and the normal force exerted by the surface on the object.\nIf you increase either of these, the frictional force is increased, likewise, if you decrease (or make zero) any of these, the frictional force is less (or zero).
211462
i believe there is no specific answer to this question as it is very relative. It would depend on various factors most importantly the purpose of the device being designed and what could be the consequence of the failure. but it should be always greater than one.
1017443
when there is no friction b/w the two bodies in contact.
920572
coefficient of kinetic friction = Friction Force / Weight\n\nFriction Force = (coefficient of kinetic friction)x(55x9.81)\n                       = 188.84 N\n\nSo Net Force = 220 -188.84 = 31.16 N\n\nF=mxa,  a=F/m=31.16/55=0.5665 m/s2
341988
Yes, the coefficient is usually a constant factor, any factor that does not contain a variable.
662183
no.  air friction will limit it's terminal velocity.  It'll still hurt, and possibly kill if it strikes someone
476031
Well, yes, neglecting any energy loss to friction (e.g. air resistance)
937470
Getting started, have to overcome static friction.  Therefore, force applied = static friction force just before movement\n\nF = umg\nF = 75N\nm = 20kg\ng = gravity\nfind u, plug and play\n\nsame problem for sliding friction