Open Query 7

course Phys 202

007. `query 6

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Question: query introset change in pressure from diameter change given original vel and diameter

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Your Solution:

The continuity equation states that A1v1 = A2v2

We’re given the diameters which can be used to calculate the Areas from pi * r^2

We also have to original velocity which can be used to calculate the new velocity from the continuity equation.

We know Bernoulli’s equation:

P1 + .5 rho v1^2 + rho*g*y1 = P2 + .5 rho v2^2 + rho*g*y2

Since the heights are the same those two terms can be cancelled.

P1 + .5 rho v1^2 = P2 + .5 rho v2^2

Change in pressure is therefore:

P2-P1 = .5 rho (v1^2 – v2^2)

Confidence Rating: 3

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Given Solution:

** The ratio of velocities is the inverse ratio of cross-sectional areas.

Cross-sectional area is proportional to square of diameter. So velocity is inversely proportional to cross-sectional area:

v2 / v1 = (A1 / A2) = (d1 / d2)^2 so

v2 = (d1/d2)^2 * v1.

Since h presumably remains constant we have

P1 + .5 rho v1^2 = P2 + .5 rho v2^2 so

(P2 - P1) = 0.5 *rho (v1^2 - v2^2) . **

Your Self-Critique: OK

Your Self-Critique Rating: OK

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Question: query video experiment 4 terminal velocity of sphere in fluid. What is the evidence from this experiment that the drag force increases with velocity?

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Your Solution:

There is evidence that the drag force increases with increased velocity because there is a smaller effect on the velocity as weight is added.

Confidence Rating: 2

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Given Solution:

** When weights were repetitively added the velocity of the sphere repetitively increased. As the velocities started to aproach 0.1254 m/sec the added weights had less and less effect on increasing the velocity. We conclude that as the velocity increased so did the drag force of the water. **

Your Self-Critique: OK

Your Self-Critique Rating: OK

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Question: query univ phy problem 14.85 (14.89 10th edition) half-area constriction then open to outflow at dist h1 below reservoir level, tube from lower reservoir into constricted area, same fluid in both. Find ht h2 to which fluid in lower tube rises.

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Question: query univ phy problem 14.85 (14.89 10th edition) half-area constriction then open to outflow at dist h1 below reservoir level, tube from lower reservoir into constricted area, same fluid in both. Find ht h2 to which fluid in lower tube rises.

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