Which of the following is true concerning a coefficient of friction? (more than
ID: 1594640 • Letter: W
Question
Which of the following is true concerning a coefficient of friction? (more than one answer can be right)
Value depends on types of surfaces in contact.
Value for rolling friction is less than for either static or kinetic friction for the same surfaces.
Can be negative.
Value for kinetic friction is less than for static friction for the same surfaces.
Can be greater than 1
a.Value depends on types of surfaces in contact.
b.Value for rolling friction is less than for either static or kinetic friction for the same surfaces.
c.Can be negative.
d.Value for kinetic friction is less than for static friction for the same surfaces.
e.Can be greater than 1
Explanation / Answer
A. Correct, value of Coefficient of friction is diffrent for different type of surfaces.
eg. for steel = 0.45 and for wood = 0.6
B. Correct, Rolling Friction is created when one surface rotates as it moves over another surface but does not slip nor slide at the area of contact. this can be find between ball bearings, it has very low value.
C. Incorrect, coefficient of friction cannot be negative, if it is possible than it means that there is no force to prevent motion.
D. Correct, the coefficient of kinetic friction is always less than the coefficient of static friction. Because if it was wrong it means that the force required to keep an object in motion would be greater than the force required to start it in motion, and that's not possible.
E.Correct, for surface rubber on steel coefficient of friction is 1.6
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