MCAT Physics Question — Blood Flow
- Sep 24, 2017
- MCAT Question of the Day
A. Decrease by approximately 10%
B. Increase by approximately 10%
C. Increase by approximately 25%
D. Remain unchanged
Click for Explanation
The problem states that Q is to remain unchanged. That allows us to set up the following equation:
Q = A1v1 = A2v2
Plugging in 1 as the original values, we get:
1 x 1 = 0.81 x v2
Because the radius was decreased to 90% of its original value, the cross-sectional area will be reduced to 81% of its original value (A is proportional to radius squared and 0.92 = 0.81)
r2 = 0.9r1
A2 = 0.81A1
Solving for v2 we get 1.23. Thus the velocity increased by approximately 25%, making choice (C) correct.
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