Engineering Board Exam Reviewer · Fluid Mechanics · hard
What is the pressure inside a water droplet 1 mm in diameter in excess of the outside pressure? ( = 0.0728 N/m)
- 291.2 Pa
- 145.6 Pa
- 582.4 Pa
- 72.8 Pa
Answer
B. 145.6 Pa
Solution
For a droplet P = 4 /d = 2 /r = 2(0.0728)/0.0005 = 145.6 Pa. (A soap bubble with two surfaces would be 8 /d.)
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