louey (cal2859) – Ch3HW1 – florin – (56930)
1
This
printout
should
have
23
questions.
Multiplechoice questions may continue on
the next column or page – find all choices
before answering.
Problem @22:
calculate the difference in
the magnitudes of the fields, not the forces.
001(part1of4)10.0points
Each part of this problem will state an ex
ample of objects interacting via some force.
Choose the fundamental interaction that is
responsible in each case.
A neutron outside a nucleus decays into a
proton,electron,andantineutrino.
1.
Gravitational
2.
Strong
3.
Weak
correct
4.
Electromagnetic
Explanation:
Notice the presence of an antineutrino in
this decay. Neutrinos (and their antiparticle
partners) only interact via the weak force, so
this must be a weak interaction.
002(part2of4)10.0points
Protons and neutrons attract each other in
anucleus.
1.
Weak
2.
Strong
correct
3.
Electromagnetic
4.
Gravitational
Explanation:
The force that holds the nucleus together
must be
strong
enough to overcome the repul
sion between protons due to the electromag
netic force. This is a strong interaction.
003(part3of4)10.0points
TheEarthpullsontheMoon.
1.
Strong
2.
Weak
3.
Gravitational
correct
4.
Electromagnetic
Explanation:
This is a gravitational interaction, in which
massive bodies attract each other.
004(part4of4)10.0points
Protonsinanucleusrepeleachother.
1.
Electromagnetic
correct
2.
Gravitational
3.
Weak
4.
Strong
Explanation:
This is an example of an electromagnetic in
teraction, in which particles with like charges
repel.
005(part1of2)10.0points
The mass of the Sun is 2
×
10
30
kg,
and
the
mass
of
Mercury
is
3
.
3
×
10
23
kg.
The distance from the Sun to Mercury is
4
.
8
×
10
10
m.
First, calculate the magnitude of the gravi
tational force exerted by the Sun on Mercury.
Use
G
= 6
.
67
×
10

11
m
3
kg
·
s
2
.
Correct answer: 1
.
91068
×
10
22
N.
Explanation:
The magnitude of the gravitational force
between two objects is given by
vextendsingle
vextendsingle
vextendsingle
vector
F
gr
vextendsingle
vextendsingle
vextendsingle
=
vextendsingle
vextendsingle
vextendsingle
vextendsingle
−
Gm
1
m
2
r
2
vextendsingle
vextendsingle
vextendsingle
vextendsingle
=
Gm
1
m
2
r
2
.
We just need to plug in the given constants to
find the answer:
vextendsingle
vextendsingle
vextendsingle
vector
F
gr
vextendsingle
vextendsingle
vextendsingle
=
Gm
1
m
2
r
2
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louey (cal2859) – Ch3HW1 – florin – (56930)
2
=
(
G
)(2
×
10
30
kg)(3
.
3
×
10
23
kg)
(4
.
8
×
10
10
m)
2
=
1
.
91068
×
10
22
N
.
where
G
= 6
.
67
×
10

11
m
3
kg
·
s
2
.
006(part2of2)10.0points
Calculate the magnitude of the gravitational
force exerted by Mercury on the Sun.
Correct answer: 1
.
91068
×
10
22
N.
Explanation:
By Newton’s third law, and by simply look
ing at the formula for the gravitational force,
it is clear that the force exerted by Mercury
on the Sun will be the same as that exerted
by the Sun on Mercury.
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 Spring '08
 Turner
 Correct Answer, Fundamental interaction, FGR

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