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Grade 11Mechanics

(a) Assuming that the drag force D is given by D = bv, show that the distance Y95 through which an object must fall from rest to reach 95% of its terminal speed is given by
height=28
where VT is the terminal speed. (Hint: Use the result for yet) obtained in Problem 17.) (b) Using the terminal speed of 42 m/s for the baseball given in Table 4-1, calculate the 95% distance. Why does the result not agree with the value listed in Table 4-1 ?

Profile image of Radhika Batra
11 Years agoGrade 11
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1 Answer

Profile image of Kevin Nash
11 Years ago
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Round off to three significant figures,
y95 = 368 m
Therefore, the baseball falls a distance of 368 m before attaining 95% of its terminal speed.
It is important to note that the value obtained above does not agree with the value given in table 4-1 ( 120 m). This is because when the baseball falls down both drag force and buoyant force acts on it. In the calculations the effect of buoyancy is neglected and eventually one ends up getting higher value than it should be.