Question

Limiting equilibrium means `ma=0` In `F-f=ma` ?

Answer 1

yes

Explanation:

In the case of limiting friction the body moves with uniform

velocity

therefore the net force must be zero and that leads to zero acceleration.

the example is a body kept on an incline ...

the net force along the incline ( at an angle `theta` from the horizontal ) is

`mg. sin (theta)` moving the body downward.

whereas the force of friction f is opposing this tendency

but f the frictional force has a limit which it can not exceed.

therefore `f = m.g. sin (theta)` or

`mg sin (theta) -f` = 0

therefore m.a =0