Version 047/AACDD – midterm 04 CC10 – turner – (57340)
1
This printout should have 17 questions.
Multiplechoice questions may continue on
the next column or page – fnd all choices
beFore answering.
001
10.0 points
Aun
i
F
o
rms
o
l
idd
i
skw
i
thr
ad
iu
sRand
mass M is mounted on a fxed axle passing
through its center (which is not shown). A
constant Force ± is applied as shown. At the
instant shown, the angular velocity oF the disk
ω
is in the

ˆ
z
direction (where +ˆ
x
is to the
right, +ˆ
y
is up, and +ˆ
z
is out oF the page,
toward you). The length oF the string is d.
The angular momentum, torque and kinetic
energy oF the disk are respectively:
1.

1
2
MR
2
ω
ˆ
z
,
RF
ˆ
z
,

1
4
MR
2
ω
2
2.
1
2
MR
2
ω
ˆ
z
,
RF
ˆ
z
,

1
4
MR
2
ω
2
3.
1
2
MR
2
ω
ˆ
z
,

RF
ˆ
z
,

1
4
MR
2
ω
2
4.
1
2
MR
2
ω
ˆ
z
,

RF
ˆ
z
,
1
4
MR
2
ω
2
5.

1
2
MR
2
ω
ˆ
z
,

RF
ˆ
z
,
1
4
MR
2
ω
2
correct
6.

1
2
MR
2
ω
ˆ
z
,
RF
ˆ
z
,
1
4
MR
2
ω
2
7.
1
2
MR
2
ω
ˆ
z
,
RF
ˆ
z
,
1
4
MR
2
ω
2
8.

1
2
MR
2
ω
ˆ
z
,

RF
ˆ
z
,

1
4
MR
2
ω
2
Explanation:
The direction oF both L and thtat oF torque
are along the

ˆ
z
direction.
The moment oF inertia oF the disk is given
by
I
=
1
2
MR
2
The magnitude oF angular momentum is
L
=
Iω
=
1
2
MR
2
ω
The magnitude oF the torque is given by
τ
=
±
R
2
+
d
2
Fsinθ
and the value oF
sinθ
is given by
sinθ
=
R
√
R
2
+
d
2
Thus, the value oF torque is
τ
=
RF
The kinetic energy is given by
K
=
1
2
Iω
2
=
1
4
MR
2
ω
2
002
10.0 points
Consider a ball with its mass 0.1 kg is head
on colliding with a leadsphere. Initially the
leadsphere is at rest and the ball is moving
along the positive x direction with a speed 6
m/s and the fnal velocity is along the negative
xdirection with a speed 4 m/s. Assume the
leadsphere is so massive that its fnal kinetic
energy is negligible compared to the kinetic
energies oF ball, both beFore and aFter the
collision. Consider Following choices For the
change in the momentum vector oF the lead
sphere
Ia. Δ
(p
lead

sphere
=Δ
(p
ball
Ib. Δ
(p
lead

sphere
=
(
0
Ic. Δ
(p
lead

sphere
=

Δ
(p
ball
and the Following choices For the change oF the
internal energy
IIa. Δ
E
int
=1
J
IIb. Δ
E
int
=
