Muraj, Hamza – Homework 24 – Due: Mar 29 2006, 4:00 am – Inst: Florin
1
This printout should have 10 questions.
Multiplechoice questions may continue on
the next column or page – fnd all choices
be±ore answering.
The due time is Central
time.
001
(part 1 o± 1) 10 points
You are using a wrench to tighten a nut.
wrench
rod
F
nut
1
wrench
F
nut
2
wrench
rod
F
nut
3
wrench
F
nut
4
Which o± the ±ollowing correctly lists the
arrangements (above) in
descending
order o±
torque magnitude?
1.
τ
3
≥
τ
2
≥
τ
4
≥
τ
1
2.
τ
2
≥
τ
4
≥
τ
3
≥
τ
1
3.
τ
1
≥
τ
3
≥
τ
2
≥
τ
4
4.
τ
2
≥
τ
1
≥
τ
3
≥
τ
4
5.
τ
3
≥
τ
4
≥
τ
2
≥
τ
1
6.
τ
4
≥
τ
2
≥
τ
3
≥
τ
1
7.
τ
3
≥
τ
1
≥
τ
2
≥
τ
4
8.
τ
2
≥
τ
4
≥
τ
1
≥
τ
3
9.
τ
1
≥
τ
2
≥
τ
3
≥
τ
4
10.
τ
2
≥
τ
1
≥
τ
4
≥
τ
3
correct
Explanation:
Basic Concepts:
τ
≡
~r
×
~
F
Solution:
The ±orce as shown is in the
x
direction.
There±ore, the perpendicular ra
dius arm is always in the
y
direction. The
longer the radius arm, the greater the torque
τ
. There±ore,
τ
2
≥
τ
1
≥
τ
4
≥
τ
3
002
(part 1 o± 1) 10 points
Given:
A circular shaped object with an inner
radius o± 10 cm and an outer radius o± 21 cm.
There are three ±orces (acting perpendicular
to the axis o± rotation) whose magnitudes are
13 N, 24 N, and 16 N acting on the object, as
shown in the fgure. The ±orce o± magnitude
24 N is 37
◦
below horizontal.
13 N
16 N
24 N
14 kg
37
◦
ω
10 cm
21 cm
Find the magnitude o± the net torque on
the wheel about the axle through the center
o± the object.
Correct answer: 3
.
69 Nm.
Explanation:
Let :
a
= 10 cm
,
b
= 21 cm
,
F
1
= 13 N
,
F
2
= 24 N
,
F
3
= 16 N
,
and
θ
= 37
◦
.
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View Full DocumentMuraj, Hamza – Homework 24 – Due: Mar 29 2006, 4:00 am – Inst: Florin
2
F
1
F
3
F
2
M
θ
ω
a
b
The total torque is
τ
=
a F
2

b F
1

b F
3
= (10 cm)(24 N)

(21 cm)
h
(13 N) + (16 N)
i
=

3
.
69 Nm
k
~
τ
k
= 3
.
69 Nm
.
003
(part 1 of 1) 10 points
A(n) 6 kg mass is attached to a string which is
wrapped several times around a uniform solid
cylinder of radius 4 m and moment of inertia
of
I
= 6 kgm
2
.
Assume:
The cylinder can rotate freely.
The acceleration of gravity is 9
.
8 m
/
s
2
.
I
= 6 kgm
2
r
6 kg
Find the torque on the cylinder.
Correct answer: 13
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 Spring '09
 Turner
 Force, Mass, Correct Answer, kg, Muraj

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