yun (bsy72) – Homework 8 – Hoffmann – (56745)
1
This
printout
should
have
10
questions.
Multiplechoice questions may continue on
the next column or page – find all choices
before answering.
001
10.0 points
A particle with charge
q
and mass
m
is un
dergoing circular motion with speed
v
.
At
t
= 0, the particle is moving along the nega
tive
x
axis in the plane perpendicular to the
magnetic field
vector
B
, which points in the positive
z
direction in the figure below.
x
y
z
vectorv
vector
B
Find the direction of the instantaneous ac
celeration
hatwide
a
at
t
= 0 if
q
is negative.
1.
hatwide
a
=
ˆ
k
+
ˆ
i
2.
hatwide
a
=
ˆ
k
3.
hatwide
a
=
ˆ
i
4.
hatwide
a
=
−
ˆ
i
5.
hatwide
a
=
ˆ
j
+
ˆ
k
6.
hatwide
a
=
−
ˆ
k
7.
hatwide
a
=
ˆ
j
8.
hatwide
a
=
−
ˆ
j
9.
hatwide
a
=
ˆ
i
+
ˆ
j
10.
hatwide
a
=
−
ˆ
k
+
ˆ
i
002
10.0 points
A particle with charge
q
and mass
m
is un
dergoing circular motion with speed
v
.
At
t
= 0, the particle is moving along the nega
tive
x
axis in the plane perpendicular to the
magnetic field
vector
B
, which points in the positive
z
direction in the figure below.
x
y
z
vectorv
vector
B
Find the period
T
of oscillation;
i.e.
, the
time it takes for the particle to complete one
revolution.
1.
T
=
m
q B
2.
T
=
q B
m
3.
T
= 2
π
m B
q
4.
T
=
m B
q
5.
T
= 2
π
q B
m
6.
T
=
2
π m
q B
003
10.0 points
On the right side of the = sign for the choices,
there should be the factor qvB. Of course
the direction is just the combination of unit
vectors in the parentheses: (X +/ Y)
A negatively charged particle moving at 45
◦
angles to both the
y
axis and
z
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 Spring '10
 Turner
 Cartesian Coordinate System, Magnetic Field, Electric charge, Versor

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