how to do
how to do two/ three block problems in NLM. is there any proper sequence or smthing to be followed .? constantly messing up these
Submerging empty container
Isothermal condition is there , and using P1V1=P2V2 , we say that here P1 and P2 r the pressures exerted on the wall by the gas , so why we r not using avg force concept for side walls and why to take h1.rho.g as this is the pressure exerted by the liquid...

Coin slipping on rotating table
Why is the frictional force acting as the centripetal force towards the center?

motion
A should not be an answer right ?
i get Vy = x * Vx and ay= Vx^2+ x*ax
also at t=0 , x=y=0 and Ux=1...

Doubt regarding free fall of block in inclined plane...
"Find acceleration (a) of Inclined plane, so that Block (m mass) will free fall",, now wherever I see the answer, it's always "For free fall N = 0, so ma sin theta = mgcos theta"...
My doubt is that, to free fall a block, all you need is mg, right? So, why only N = 0, ma should be = 0 also.. even, N should cancel ma.. so that only mg remains.. but if we do N=0 its just Normal force being 0, the horizontal acceleration remains there.
I think N = mgcos theta should be answer.. but it isn't...
Complex No.s
had solved the whole question but the answer i got was arg(z2) = pi/4 and arg(z1) = 3pi/4

Molar mass chemistry
I see questions in which they make use of molar mass of like Xe , I etc , ik molar mass till like 20ish atoms and some general ones like Cl Ag , is it necessary to remember molar masses for adv , if yes which which