Open Query 7

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course Phy 122

007. `query 6*********************************************

Question: query introset How do we find the change in pressure due to diameter change given the original velocity of the flow and pipe diameter and final diameter?

Your Solution:

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

Thus

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

confidence rating #$&*:

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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. I could have gone into a little more detail and showed exactly where I got my first equation.

Your Self-Critique Rating: 3

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Question: query video experiment 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:

As the velocities got larger, the added weights stopped affecting the increase of velocity.

confidence rating #$&*:

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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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&#This looks very good. Let me know if you have any questions. &#