homework 01 – FONTENOT, BRIAN – Due: Jan 21 2008, 4:00 am
1
Question 1, chap 1, sect 1.
part 1 of 2
10 points
Two points in the
xy
plane have cartesian
coordinates (
x
1
, y
1
) and (
x
2
, y
2
), where
x
1
=
9
.
3 m,
y
1
=
−
10 m,
x
2
=
−
10 m, and
y
2
=
5
.
4 m.
Determine the distance between these
points.
Answer in units of m.
Question 2, chap 1, sect 1.
part 2 of 2
10 points
What is the angle between the line con-
necting the two points and
x
-axis (measured
counter-clockwise, within the limits of
−
180
◦
to +180
◦
)?
Answer in units of
◦
.
Question 3, chap 1, sect 6.
part 1 of 1
10 points
The velocity of a transverse wave traveling
along a string depends on the tension of the
string,
F
, which has units of force, and its
mass per unit length,
μ
.
Assume
v
=
F
x
μ
y
. The powers of
x
and
y
may be determined based on dimensional
analysis.
The values of
x
and
y
for this problem are
1.
x
=
−
1
2
, y
=
1
2
2.
x
=
−
1
2
, y
=
−
1
2
3.
x
= 1
, y
=
−
1
4.
x
=
1
2
, y
=
1
2
5.
x
=
−
1
, y
=
−
1
6.
x
= 0
, y
= 1
7.
x
= 1
, y
= 0
8.
x
=
−
1
, y
= 1
9.
x
=
1
2
, y
=
−
1
2
10.
x
= 1
, y
= 1
Question 4, chap 1, sect 6.
part 1 of 3
10 points
There are roughly 10
59
neutrons and pro-
tons in an average star and about 10
11
stars
in a typical galaxy. Galaxies tend to form in
clusters of (on the average) about 10
3
galax-
ies, and there are about 10
9
clusters in the
known part of the Universe.
Approximately how many neutrons and
protons “#” are there in the known Universe?
1.
#
≈
10
87
2.
#
≈
10
43
3.
#
≈
10
52
4.
#
≈
10
82
5.
None of these
6.
#
≈
10
47
Question 5, chap 1, sect 6.
part 2 of 3
10 points
Suppose all this matter were compressed
into a sphere of nuclear matter such that
each nuclear particle occupied a volume of
1
.
401
×
10
−
45
m
3
(which is approximately the
“volume” of a neutron or proton).
What would be the radius of this sphere of
nuclear matter?
1.
None of these
2.
R
≈
10
25
m
3.
R
≈
10
23
m
4.
R
≈
10
12
m
5.
R
≈
10
14
m