Question

Can we apply equation of motion when there is non-conservative force in the question??

Answer 1

yes, of course you can apply equation of motion. actually, equation of motion is based on Newtonian dynamic equation. and you know as well, Newtonian equation is valid when frame of reference is inertial. it is independent from conservative or non - conservative force.

conservative means we can retrieve it while non-comservative means we can't retrieve it. for instance, electric force, magnetic force etc.. are conservative and frictional force is non-conservative.

eventually, equation of motion can't apply for non-inertial frame of reference. but you are always free to apply equation in case of non-conservative force.