Q.

A cylindrical tube AB of length l, closed at both ends, contains an ideal gas of 1 mol having molecular weight M. The tube is rotated in a horizontal plane with constant angular velocity ω about an axis perpendicular to AB and passing through the edge at end A, as shown in the figure. If PA and PB are the pressures at A and B respectively, then

(consider the temperature is same at all points in the tube)                         [2026]

1 PB=PAexp(Mω2l22RT)  
2 PB=PAexp(Mω2l23RT)  
3 PB=PAexp(Mω2l2RT)  
4 PB=PA  

Ans.

(1)

A[(P+dP)-P]=(dm)(ω2x)

dP=(dm)Aω2x

dP=(ρ)(A)(dx)ω2xA

also [PM=ρRT]

ρ=PMRT

dP=(PMRT)ω2xdx

PAPBdPP=ω2MRT0xdx

n(PBPA)=ω22M2RT

PB=PAeMω222RT