A 13 g coin slides upward on a surface that is inclined at an angle of 12° above the horizontal. The coefficient of kinetic friction between the coin and the surface is 0.23; the coefficient of static friction is 0.31. Find the magnitude and direction of the force of friction under the following circumstances.
(a) after it comes to rest?
Whats the answer and how is it done. I cant figure out what to do.
2007-11-04 03:24:01 · 1 answers · asked by Anonymous in Science & Mathematics ➔ Physics
The force of friction can be at most equal in magnitude to the product of the normal force and the coefficient of friction (kinetic if in motion, static if stationary), u. However, the force of friction always opposes any motion, and thus any applied force in the direction of motion, but it cannot exceed it in magnitude (otherwise, the object would fly off in the direction opposite the applied force). On an incline of angle theta, the normal force is equal to mg*cos(theta) and the force of gravity along the incline is equal to mg*sin(theta). So calculate the maximum force of friction Ff = umg*cos(theta) and the force of gravity (in the direction of the incline) Fg = mg*sin(theta). If Ff is greater than Fg, which should be the case, then the force of friction is equal to Fg, upwards along the incline, rather than its maximum value of Ff. However, if Fg is greater than Ff, this is really a trick question because the coin wouldn't come to rest in that case.
2007-11-06 10:29:54 · answer #1 · answered by DavidK93 7 · 0⤊ 0⤋