# Friction law

Can you please describe the formula of velocity?

The relationship between the frictional force and the relative velocities of two surfaces in contact depends on the amount of lubrication (if any) and the pressure  between the surfaces, among other things.  It's not a simple matter.  What problem are you trying to solve?
ianmoth
06 November 2014
Well, the velocity is the displacement (s)* of an object over a period of time (t), so:v = s / tI'm not sure where you think friction comes into the formula? If the forces on an object are constant then the velocity will remain constant.If a new force is added, or one of the forces acting on an object changes then the object will speed up or slow down or change direction, thus the displacement* will change.Please give us some more detail so we can help you out with the friction part - what level are you working at and which exam board?* displacement is as opposed to distance when calculating speed (speed = distance / time)... Velocity is known as a vector quantity, in that it has direction as well as size. The velocity from your home to school will be different to your velocity travelling from school to home, even if the speed you travel is the same.
jamxmitchell
07 November 2014
Friction is a force that comes into play because of two surfaces in contact. A force gives rise to an acceleration or change in velocity, in accordance with the newton's laws.Now,do you want to know about the concept of "terminal velocity" or "viscosity in Fluids" (both are realization of frictional force)?
premkumar
27 November 2014
Velocity is the displacement over time, or V = S / T.  Remember that velocity is a vector, so it has both direction and magnitude.  You units for velocity should be m/s.When you mentioned friction, I assume that you are dealing with something along the line about moving blocks and tension cords?  If in that case, you must sum all forces in the x and y to be 0 since everything is in equilibrium.  ΣFx=0, ΣFy=0, and your frictional forces (Fx & Fy) im the x direction is Fx= μmg cos(theta) and for y direction Fy= μmg sin(theta).   Theta is the angle in degrees.Hope this helps a bit.
kiss
06 December 2014
v=s/t. Velocity is a vector physical quantity; both magnitude and direction are required to describe the velocity. where s =displacement and t= tme.
mujtaba
04 January 2015