Mark the correct statement(s) about the friction between two bodies

a) Static friction is not always greater than kinetic friction because ${\text{f}}_{\text{s}}$  takes the values from 0 to ${\text{f}}_{\text{ms}}$  where ${\text{f}}_{\text{k}}$  take place less than ${\text{f}}_{\text{ms}}$ .

b) Obviously coefficient of static friction is always greater than coefficient of kinetic friction.

i.e. ${\text{μ}}_{\text{s}}=\frac{{\text{f}}_{\text{ms}}}{\text{N}},{\text{μ}}_{\text{k}}=\frac{{\text{f}}_{\text{k}}}{\text{N}}\text{we}\text{know}{\text{f}}_{\text{k}}<{\text{f}}_{\text{ms}}$  

Therefore we get ${\mu }_k<{\mu }_s$ .

c) It is true that limiting friction is always greater than kinetic friction.

${\text{f}}_{\text{ms}}>{\text{f}}_{\text{k}}$ .

${\text{f}}_{\text{ms}}$  is the maximum strength of interlocking of irregularities between two surfaces in contact which are at rest.

${\text{f}}_{\text{k}}$  is strength of interlocking of irregularities between two surfaces in contact having relative motion.

d) Limiting friction ${\text{f}}_{\text{ms}}$  is maximum value attained by the static

friction so ${\text{f}}_{\text{ms}}$  will never be less than static friction ${\text{f}}_{\text{s}}$ .