Chem 110A
Midquarter ANSWERS Name_Student ID_VERSION A ANSWERS Midquarter Exam November 6, 2009 Chemistry 110A Professor McCurdy
Instructions: You may use only a pencil or pen. You may have one sheet of equations that you have prepared yourself. No other

Chem 110A Name_ Student ID_
Midquarter Exam November 6, 2009 Chemistry 110A Professor McCurdy Instructions: You may use only a pencil or pen. You may have one sheet of equations that you have prepared yourself. No other materials are allowed. Write all an

Chem 110A Name_Answers_ Student ID_
Second Midquarter Exam November 25, 2009 Chemistry 110A Professor McCurdy Instructions: You may use only a pencil or pen. You may have one sheet of equations that you have prepared yourself. No other materials are allow

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Biological Sciences 102 Winter, 2010 K. Hilt Assigned text problems: Biochemical Calculations (Segel)
Homework #3
4-4 on pp. 223-224 and 4-9 on pp. 237-238 pp. 319 #2, 3, 6, 10, and 12. You need to be able to plot and interpret Lineweaver-Burk grap

ECH 142 NAME: vcm NC)
Quiz 1 3"
(B Form)
#1) (5 points)
The local Nusselt number for turbulent heat transfer over a plate is
given by
NW = 0.0290 (NW) (M9043
, where x is the distance from the beginning edge of the plate. Drive
the rela

ECH 142
Chemical Engineering Heat Transfer
HOMEWORK 3 SOLUTION
Problem 1
The function of the extra clothing in winter is to trap a layer of stagnant air near the skin, thereby decreasing the effect
of convective heat transfer. Since the students are wear

ECH 142
Problem Set #5
Due Thursday 4/30/15
1. A cylindrical steel rod with diameter 1.75 and length 18 is connected to steel plates at the boiling
point and freezing point of water, respectively (i.e., at 212F and 32F). The ambient air termperature
is 72

ECH 142
Problem Set #7
Due Thursday 5/14/15
1. Shown below is a diagram of a circuit board with dimensions 14cm x 8 cm, on which are located 16
integrated circuits (ICs) with cross-sectional dimensions 1cm x 1cm. The circuit board is 1mm thick,
has an ave

ECH 142
Problem Set #4
Due Wednesday 4/22/15
1. An irregularly shaped object with an initial temperature of T0=60C is placed in a well-stirred batch
that is maintained at TB=70C. Next the same object, but with an initial temperature of T0=95C, is
placed i

ECH 142
Problem Set #6
Due Thursday 5/6/15
1.
In class we used separation of variables to derive the temperature field in a rectangular region. The
result was
T(x, y) = Bn sin(nx) sinh(ny) ,
n=1
with the coefficients defined by
1
2
Bn =
f(x )sin (nx)dx .

ECH 142
Problem Set #3
Due Thursday 4/16/15
1. A spherical tank is to be used as a container for liquefied petroleum gas. The tank is to have a wall
comprised of two layers, as shown in the figure below. The inner radius of the inner layer is r0, the
sphe

Problem Set #2
Due Thursday 4/9/2015
1. The Second Law of Thermodynamics is typically written in the form dSdQ/T, where S is entropy,
Q is the total heat flow into a system and T is temperature. The same law may be expressed as an
integral balance in the

Problem Set #2
Due Wednesday 4/14
1. The planar, composite wall shown below consists of common building brick (k=0.72W/mK) and
fiberboard sheathing (k=0.06 W/mK). The wall is in contact with air on both sides, with the
temperatures and heat transfer coeff

Homework #3
Due Tuesday, April 23, 2013
1. A pipe has a single-layer wall of thickness r2r1 and thermal conductivity k1. To try to
prevent heat losses from the outside of the pipe, we add a second layer material to the outside,
with thickness r3r2 and wit

Homework #2
Due Tuesday, April 16, 2013
1. a. For water at room temperature exposed to a roughly 10 C temperature change, determine
how large the velocity would have to be for Br > 1.
~
b. Justify the expectation that T ~ 1 for gases.
2. A semi-infinite s

Homework #1
Due Tuesday, April 9, 2013
1. Use a material body control volume to
a. derive the continuity equation (conservation of mass). Clearly explain all steps.
b. Using your result from part a, convert Leibniz rule (Reynolds transport theorem)
d
$( "

Homework #4
Due Monday, April 29th, 2013
In class (no late HW's accepted)
1. Consider one-dimensional transient heat conduction occurring over short times < L2/. At this
time scale, the characteristic distance over which T varies spatially is defined as ,

ECH142 HW4 Solution, Spring 2013
1a
One-dimensional transient conduction:
T
2T
= 2
t
x
Scale variables: =
T Tref ~ x ~ t
;x = ;t =
T
T T 2
=
~
t
2 ~ 2
x
Divide by
2
:
2 2
=
~ ~ 2
t
x
1b
2
If
> 1, ~ 0 is constant and we cannot satisfy both I.C. and