七、請由空氣、水、廢物三大面向說明新冠肺炎(COVID-19)對環境帶來的衝擊。 (10%)

(a) At an instant after it passes B, the normal force exerted by the road on the car drop to one-third of the normal force at point A. Please determine the θ. (15%)

(b) If the car speed is variable, what is the minimum speed that will cause the car to lose contact with the road at the highest point C ? (10%)

(2) (Please see Fig. 2) Three identical small spheres, each of mass 1 kg, can slide freely on a horizontal frictionless surface. Spheres B and C are connected by a light rod and are at rest in the position shown when sphere B is struck squarely by sphere A which is moving to the right with a velocityVo= 2.4 m/s. Knowing that θ = 45°and that the velocities of spheres A and B immediately after the impact are and ， determine (a) (9%); and (b) the velocity of sphere C immediately after impact. (16%)

(3) (Please sce Fig. 3) The homogeneous sphere of mass m and radius r is projected along the incline of angleθ with an initial speed v0 and no angular velocity (ω0 = 0). If the coefficients of static and kinetic friction are μs and  μk, respectively, determine the time duration t of the period of slipping (10%). In addition, find the velocity v of the mass center G and the angular velocity ω at the end of the period of slipping.(7% and 8%, respectively)

(4) (Please see Fig. 4) As shown in Fig. 4, the crank AB rotates with a constant angular velocity of 600 rpm clockwise. Please determine: (1) the angular velocity of the connecting rod BD (10%); (2) the angular acceleration of the connecting rod BD (10%); (3) the acceleration of point D on the piston. (5%)

1.(20 %) Please explain each of the terms in the following (2 pts each). (a) Reynold number, (b) molecular momentum flux, (c) Prandtl mixing length, (d) velocity potential, (e) Reynolds stress, (1) form drag, (8) fanning friction factor, (h) eddy diffusivity, (i) divergence of velocity, () creeping flow.

2. (8%) Introduce the following dimensionless terms into the Navior-Stokes equation: u* =u/u∞, dimensionless velocity P* =P/ρu∞2, dimensionless pressure t*=t u∞/L, dimensionless time x* =x/L, dimensionless distance The operator∇ may then written ∇*/L. Show that the Navior-Stokes equation becomes

(a) (2 pts) Calculate the void fraction ε.

(b) (3 pts) Calculate the effective diameter Dp of the particles.

(c) (2 pts) Calculate the ratio of total surface area in the bed to total volume of bed in m"

110年 - 110 國立中山大學碩士暨碩士專班招生考試_環工所碩士班:環境工程概論#105956

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110年 - 110 國立中央大學_碩士班招生考試_應用地質研究所：環境工程概論#103852