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Unformatted text preview: Fall ’03 Uniﬁed Engineering I
Problem U2 (Uniﬁed Concepts) Dimensions and units are fundamental to the language of engineering. This question is an
exercise in this important topic. You may have to use common sense and perhaps a little
research to answer some of the questions. The tables in the front of Crandall, Dahl, and
Lardner should b e helpful. The SI, British, and other unit systems all have well-deﬁned
units and symbols, Answers which are not accompanied by the correct symbol or unit are
not eligible for full credit, in this question and in the rest of Uniﬁed.
a) Conversion. A strong cyclist is generating a steady 0.4 hp. How much power is this in
SI and British units?
b) Estimation. The cyclist also generates waste heat at a rate of three times the mechanical
p ower. If the cyclist’s b ody wasn’t being continuously cooled, roughly how long could he
maintain this p ower output?
Hint: Assume the human b ody has the same heat capacity as water.
c) Analysis. You will learn in Fluids that the aerodynamic lift L and pitching moment M
on a wing depend on the air density �, air velocity V , wing area S , and wing chord c. Good
approximations to measured data are found to be:
�V S CL
�V S c CM
L= What are the dimensions of the lift coeﬃcient CL and the pitching moment coeﬃcient CM ?
d) Scaling. If the wing in c) is geometrically scaled down by a factor of 1/2, and is operated
in the same airﬂow conditions as the full-size wing, how much do you expect the lift and the
moment to change? ...
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This note was uploaded on 01/28/2012 for the course AERO 16.01 taught by Professor Markdrela during the Fall '05 term at MIT.
- Fall '05