EGR 102
of 4 pages
Lecture HW 01
1
EGR 102 Lecture HW 01
Due at beginning of lecture on Friday, January 20
4 Problems, 4 Points Each, 16 Points Total
Name:
PID:
Problem 1 (4 pts):
A group of 30 students attend a class in a room that measures 10m by 8m by 3m.
Each student
takes up 0.075 m
3
and gives out 80W of heat (1W = 1 J/s).
Calculate the air temperature rise
during the first 15 minutes of the class if the room is completely sealed and insulated.
Assume
heat capacity,
C
v
, for air is 0.718 kJ/(kg K).
Assume air is an ideal gas at 20°C and 101.325
kPa.
Note that the heat absorbed by the air
Q
is related to the mass of the air
m
, the heat
capacity, and the change in temperature by the following relationship:
Q = mC
v
(T
2
T
1
)
The mass of the air can be obtained from the ideal gas law:
PV
=
mRT / Mwt
Where
P
is the gas pressure,
V
is the volume of the gas,
Mwt
is the molecular weight of the gas
(for air, 28.97 kg/kmol), and
R
is the ideal gas constant [8.314 kPa m
3
/(kmol K)].
This preview has intentionally blurred sections. Sign up to view the full version.
View Full Document
This is the end of the preview. Sign up
to
access the rest of the document.
 Fall '08
 HINDS
 MWt, Lecture HW

Click to edit the document details