13·The friend (m-60 kg) in the previous problem, also on ice, catches the ball b

Question

13·The friend (m-60 kg) in the previous problem, also on ice, catches the ball bringing it to rest, the impulse on the ball is a) -6 Ns b)-12 Ns c)-7 Ns d)-720 Ns 14. An airplane wing uses a design shown in the figure to produce lift. If the angle of the wing with respect to the forward motion is at maximum lift, just before a stall, the air flow around the wing is a) laminar and faster on the bottom of the wing b) laminar and faster on the top of the wing c) turbulent and faster on the bottom of the wing d) turbulent and faster on the top of the wing 15. The flow rate of blood flowing through a small blood vessel or IV where viscosity is an important factor is most accurately determined by using a) Bernoulli's law b) Stoke's law c) Poiseuille's law d) Continuity equation Two equations govern the drag of an object in a fluid. Which one is used when the velocity of the object is fast in the fluid and the flow is turbulent? (remember in this case the object is pushing against the fluid and the work of drag is equal to the kinetic energy of the fluid displaced) 16. Drag = 12Dv Drag =1/2CpAv2 a) b) 17. Hydraulic systems utilize Pascal's principle by t transmitting pressure from one cylinder (called a master) to another (called a slave). A certain hydraulic system is designed to exert a force 70 times as large as the one put into it. If the area of the inlet piston is 3 cm2, what is the diameter of the large outlet piston? a) 180 cm b) 66.8 cnm c) 16.4 cnm d) 8.2 cm

Explanation / Answer

Hi,

13. The answer for this questions depends on other question that is not shown, therefore I cannot give you an answer.

14. The answer for this should be letter b, as the flow through the wing of a plane is an example of laminar flow. Besides, the air should be faster above the wing because in that way the pressure above it will be lower than below. That pressure difference will maintain the plane in the air.

15. In this case the answer should be letter c (Poiseuille's law), as this law deals with flows with very low values of Reynolds number, where viscosity is relatively high.

16. The answer for this question should be letter b, because that equation can be deduced if the fluid is turbulent and the object is moving fast enough inside said fluid (in fact, the factor 1/2 is the connection between this equation and the equation for the kinetic energy).

17. The physic principle behind this question is as follows:

P1 = P2 ::::::: (F1/A1) = (F2/A2) ::::::::: (F2/F1) = (A2/A1) = n ; where n is the factor they mention (70 in this case)

Besides: A = D2 /4 :::::::: (3 cm2) = D12 /4 :::::::: D1 = 1.95 cm

Therefore, the value of the diameter of the outlet piston would be:

(A2/A1) = (D2/D1)2 = 70 :::::::: D2 = D1 (8.37) :::::::: D2 = 16.4 cm

So the answer is letter c.

I hope it helps.

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