Name
___________________________________
Student ID Number
____________
last
first
I.
A pump (not shown) pulls water
through a tube from point Q past
point R. The tube radius changes
from 21
.
0 cm at Q to 5
.
00 cm at R.
Point Q is 81
.
0 cm below water level in a
large lake. Point R is 39
.
0 cm above the lake. P
0
= 1
.
013
×
10
5
Pa.
The water has constant density 1000 kg/m
3
, and is known to
have speed 14
.
0 cm/s at point Q. Ignore turbulence, viscosity,
etc., and assume ideal flow conditions. Use g = 9
.
81 m/s
2
.
water level
air P
0
Q
•
81
cm
39
cm
•
R
1.
(5 pts) Which choice best represents the area (cross-section) of the tube at point R?
1
.
96
×
10
-3
m
2
1
.
96
×
10
-1
m
2
7
.
85
×
10
-3
m
2
1
.
81
×
10
-1
m
2
none of these
A
B
C
D
E
π
r
2
2.
(5 pts) Which choice best represents the pressure at point Q?
9
.
34
×
10
4
Pa
9
.
96
×
10
4
Pa
1
.
03
×
10
5
Pa
1
.
09
×
10
5
Pa
8
.
96
×
10
5
Pa
A
B
C
D
E
Bernoulli relates pressures at R and Q
3.
(5 pts) Which choice best represents the water speed at point R?
3
.
00 m/s
0
.
624 m/s
2
.
47 m/s
3
.
25 m/s
4
.
30 m/s
A
B
C
D
E
A
1
v
1
= A
2
v
2
Physics 115B, Winter 2008, version D
Exam 1, page 1

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