physics help needed?

Question

1. the kinetic friction of one metal object sliding along another metal surface depends least upon?
a. the coefficient of kinetic friction
b. the noraml force
c. the nature of matierals in contact
d. the area of contact

I think it's C but i could be wrong, explain to me if i am...

Answer 1

Coulombs law of friction is

F = mR

where

m (mu) = coefficient of friction is this case the kinetic coefficient
R = normal reactive force
F = frictional force

So to answer your question

a - definately as F is directly propertional to mu
b - yes again F is directly proprtional to R
c - this determines the coefficient of friction
d - has no effect on F so this is the answer

So D is the answer

Answer 2

C is the answer; the kinetic friction depends on the roughness or the smoothness of the surface involved so if the surface is rough which means it will increase the friction; and if it smooth it reduces. So in simple terms it depends on the nature of material in contact.

Answer 3

force of kinetic friction = F
coefficient of kinetic friction = k
Normal force = N

there's a law that says : F = k x N

so the force of friction depends on the cofficient of kinetic friction and the normal force. Since the cofficient of friction depends on the material used, the force of friction also depends on the nature of materials in contact. So all A,B and C are correct

Happy Holidays

Answer 4

should be d:
friction=(coef. of friction)(norm.force); therefore not a/b
I believe the nature of the materials determines the coeff.; so it shouldnt be c.

Answer 5

C and u aint rong x

Answer 6

d

Answer 7

d

Answer 8

i think c to