625_Physics ProblemsTechnical Physics

# 625_Physics ProblemsTechnical Physics - Chapter 21 P21.64...

This preview shows page 1. Sign up to view the full content.

Chapter 21 627 P21.64 (a) The effect of high angular speed is like the effect of a very high gravitational field on an atmosphere. The result is: The larger-mass molecules settle to the outside while the region at smaller r has a higher concentration of low-mass molecules. (b) Consider a single kind of molecules, all of mass m. To cause the centripetal acceleration of the molecules between r and rd r + , the pressure must increase outward according to Fm a rr = . Thus, PA P dP A nmAdr r −+ = af bg ej ω 2 where n is the number of molecules per unit volume and A is the area of any cylindrical surface. This reduces to dP nm rdr = 2 . But also Pn kT B = , so dP k Tdn B = . Therefore, the equation becomes dn n m rdr B = 2 giving dn n m rdr n n B r 0 2 0 zz = or ln n m r n n B r 0 22 0 2 = F H G I K J ln n n m r B 0 2 2 2 F H G I K J = and solving for n : nn e mr k T B = 0 2 . P21.65 First find v av 2 as v N vNd v v av 2 = z 1 2 0 . Let a m B = 2 . Then, v Na N ve a a a m av dv B av 2 == = z 4 4 3 8 3 12 32 4 0 32 12 2 2 π The root-mean square speed is then
This is the end of the preview. Sign up to access the rest of the document.

## This note was uploaded on 12/14/2011 for the course PHY 203 taught by Professor Staff during the Fall '11 term at Indiana State University .

Ask a homework question - tutors are online