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51.

The Graetz number (NGz) is defined as

A.	NRe NPr	B.	NRe NPr/NNu
C.	(NRe NPr)(D/L)	D.	(NRe)(D/L)

52.

The Prandtl number is

A.	the ration of kinematic viscosity to thermal diffusivity	B.	the ratio of thermal diffusivity to kinematic viscosity
C.	the product of thermal diffusivity and kinematic viscosity	D.	the ratio of absolute viscosity to thermal conductivity

53.

The coefficient of volume expansion for an ideal gas is

A.	P/RT	B.	R/P
C.	R2T/P2	D.	1/T

54.

Transition from laminar to turbulent flow in a natural convection on vertical plates occurs when the product of the Prandtl number and the Grashof number equals approximately

A.	10?	B.	2100
C.	10?	D.	4000

55.

In natural convection fluid moves under the influence of

A.	buoyant forces arising from changes in density	B.	changes in fluid pressure produced by external work
C.	surface tension forces	D.	elastic forces

56.

In forced convection fluid moves under the influence of

A.	changes in fluid pressure produced by external work	B.	buoyant forces arising from changes in density
C.	elastic forces	D.	surface tension forces

57.

The Graetz number is associated with

A.	heat transfer by radiation	B.	heat transfer in laminar flow
C.	heat transfer in turbulent flow	D.	mass transfer operations

58.

The Grashof number is proportional to

A.	the ration of viscous force to buoyance force	B.	the ration of buoyancy force to viscous force
C.	the ration of buoyancy force to elastic force	D.	the ration of viscous force to inertial force

59.

The Peclet number is a measure of the ratio of

A.	energy transport by conduction to that by convection	B.	energy transport by convection to that by conduction
C.	buoyancy force to viscous force	D.	kinematic viscosity to thermal diffusivity

60.

The hydrodynamic and thermal boundary layers are identical when

A.	Npr = 0.7	B.	NPr = 1
C.	NPr = 1.5	D.	NPr = 120