AME 101 Fall 2007
Problem Set #6
Assigned: Friday, 11/30/2007
Due: Friday, 12/7/2007, 2:00 pm, in my mailbox (OHE 430J).
Note earlier due time – 2:00 PM
not 4:30 PM.
As always, no late homework is accepted for credit
(you may turn in late homework,
however, if you just want it graded.)
Note:
Since your lowest homework grade will be dropped anyway, if you’re satisfied with your other
5 scores, you can skip this assignment. (Though I recommend doing these problems anyway, you’ll
need to know the material for the final exam!)
Problem #1 (scrutiny) (15 points)
Using the First Law of Thermodynamics I derived the following formula for the exhaust velocity
(
v
out
) of a new type of rocket engine in terms of the exhaust temperature (
T
out
), inlet temperature (
T
in
)
and specific heat (
C
P
):
v
out
=
2
C
P
(
T
in
"
T
out
)
The formula has already passed the usual smoke, function and performance tests.
(a) For each of the following 4 assumptions, state whether or not this assumption was required to
derive the above result, and explain why in 1 or 2 sentences.
NO CREDIT WITHOUT
EXPLANATION !!!!
(i) Steady flow
(ii) Ideal gas
(iii) Constant specific heat (C
P
)
(iv) Incompressible fluid
(b) List
TWO AND ONLY TWO
other assumptions, not listed in part (a), that were required to
obtain this result. (There are at least 4 other assumptions, but just pick the two that you are most
sure of.)
Problem #2 (thermodynamics) (15 points)
a)
How much energy (in Joules) is required to heat 1 gallon of liquid water from 0˚C to 100˚C?
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 Fall '07
 Ronney
 Energy, Heat, Heat Transfer, heating value, Radiative heat transfer

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