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Week 10
1
What is the strength of the gravitational
force with which the Earth pulls on you?
MEarth = 5.98x1024 kg
REarth = 6.37x106 m
Week 10
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2
Astrologers believe that the forces of the planets and stars at
the time of your birth determine key personality attributes and
your fate in life.
Could the force be gravity?
What is the gravitational force with which Jupiter pulls on you
when it is closest to earth?
What is the gravitational force with which the person next to
you pulls right now?
MJupiter = 1.9x1027 kg
djupiter = 7.78x1011 m
dEarth =
Week 10
1.5x1011
m
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3
Astrologers believe that the forces of the planets and stars at
the time of your birth determine key personality attributes and
your fate in life.
Could the force be gravity?
What is the gravitational force with which Jupiter pulls on you
when it is closest to earth? FJupiter on you = 2.4x10-5 N
What is the gravitational force with which the person next to
you pulls right now? Fclassmate on you = 3.8x10-5 N
MJupiter = 1.9x1027 kg
djupiter = 7.78x1011 m
dEarth =
Week 10
1.5x1011
m
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4
Week 10
5
What is the escape speed of a particle on the
“surface” of the sun?
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Week 10
6
Sagittarius A* is a bright radio source. What is the
mass of Sag A*? How many times the mass of
the sun is this?
1 light day = 2.6x1013 m
1 year  πx107 sec
Msun = 2x1030 kg
Week 10
7
Week 10
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Week 10
9
A particle is undergoing simple harmonic
motion. What are its
• Amplitude?
• Period?
• Angular frequency?
• Maximum velocity?
• Phase constant?
6
5
4
3
position [m]
2
1
0
0
0.05
0.1
0.15
0.2
0.25
0.3
0.35
0.4
0.45
0.5
0.55
0.6
0.65
-1
-2
-3
-4
-5
-6
time [sec]
Week 10
10
A 160 g mass on a 1.0 m-long string is
pulled 6.7o to one side and released.
How long does it take for the pendulum to
reach 2.9o on the opposite side?
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Week 10
11
The 20 cm-long wrench in the figure
swings on its hook with a period of 0.88 s.
When the wrench hangs from a spring of
spring constant 350 N/m, it stretches the
spring 3.5 cm. What is the wrench's
moment of inertia about the hook?
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Week 10
12
The 15 g head of a bobble-head doll
oscillates in SHM at a frequency of 4.0 Hz.
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* What is the spring constant of the spring
on which the head is mounted?
* Suppose the head is pushed 2.0 cm
against the spring, then released. What is
the head's maximum speed as it
oscillates?
Week 10
13
Week 10
14