A traffic flow on a freeway is very dense and it is proposed that a fluid flow could possibly simulate the flow. If it was decided to study the feasibility of the proposal, which flow would be a possibility?

(A) An incompressible flow
(B) A compressible flow with M < 1
(C) A compressible flow with M > 1
(D) A compressible flow with M = 1


(C) A compressible flow with M >1
Consider a primary characteristic of an incompressible flow or a subsonic flow: as the area decreases, the velocity increases. For a supersonic flow, as the area decreases the velocity decreases. We all know that when a traffic flow encounters a decrease in the number of lanes, the traffic slows down, it does not speed up. So, it would require a compressible flow model with M > 1.

Physics & Space Science

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The force in member FE of the plane truss below is approximately:



(A) 21.5 kN
(B) 22.2 kN
(C) 3.9 kN
(D) 4.7 kN

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If at least one component of a vector is a positive number, the vector cannot

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A 0.40-kg mass, attached to the end of a 0.75-m string, is whirled around in a circular horizontal path. If the maximum tension that the string can withstand is 400 N, then what maximum speed can the mass have if the string is not to break?

a. 370 m/s c. 19 m/s b. 27 m/s d. 29 m/s

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