As these four equations show the coefficient of kinetic friction [[micro].sub.k] and the wall-normal restitution coefficient [e.sub.n] have to be known to calculate the particle velocity after the wall collision.

[20] investigated the coefficient of kinetic friction between an ice cone and different materials with smooth surfaces.

When you go for a Chinese meal always take with you a measuring tape, a pocket calculator, a table of values of the

coefficient of kinetic friction for various food types and a spring balance to measure the weight of each mouthful.

The

coefficient of kinetic friction between the block and the horizontal surface is assumed to be constant and will be denoted by [mu].

After slip, the coefficient of static friction changes to the coefficient of kinetic friction. Including viscous effects dictates the use of Newton's law of viscosity as well.

Since the coefficient of kinetic friction is smaller than the coefficient of static friction, the torque resulting from dry friction after slip is lower than that required to start slip.