007 query 7

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course PHY 202

007. query 7 was submitted 15 Jun 2011 around 8:12 AM.

007. `query 7*********************************************

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?

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Your Solution:

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

Continuity equation: (A1 / A2) = v2 / v1 = (d1 / d2)^2, so it follows that:

v2 = (d1/d2)^2 * v1

Since h presumably remains constant we have

P1 + 0.5 rho v1^2 = P2 + 0.5 rho v2^2

(P2 - P1) = 0.5 *rho (v1^2 - v2^2) so therefore:

• v2 = (A1 / A2 ) * v1

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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: 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:

The speed of the sphere repetitively increased when weights were repetitively added. As the velocities began to approach 0.1254 m/ s the added weights had less effect and as the speeds began to approach 0.1254 m/s the added weights had less effect as well. And as the speed increased so did the drag force of the water.

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 approach 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: 3

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