madrid (tmm2353) – HW 51 – Antoniewicz – (56445)
1
This printout should have 26 questions.
Multiplechoice questions may continue on
the next column or page – fnd all choices
beFore answering.
001 (part 1 of 7) 2.0 points
A box oF mass 45 kg hangs motionless From
two ropes, as shown in the fgure below. The
angle is 37
◦
. Choose the box as the system.
The
x
axis runs to the right, the
y
axis runs
up, and the
z
axis is out oF the page.
Rope 1
Rope 2
37
◦
Is
dvp/dt
oF the box zero or nonzero?
1.
Zero
correct
2.
Nonzero
3.
Unable to determine
Explanation:
The box is in static equilibrium, so the net
Force on the box is zero.
002 (part 2 of 7) 2.0 points
Which oF the Freebody diagrams in the Fol
lowing fgure correctly describes the Forces
acting on the box?
I
b
v
F
T
2
(rope 2)
v
F
T
1
(rope 1)
II
b
v
F
T
2
(rope 2)
v
F
grav
(Earth)
III
b
v
F
T
2
(rope 2)
v
F
grav
(Earth)
v
F
T
1
(rope 1)
IV
b
v
F
T
2
(rope 2)
v
F
grav
(Earth)
v
F
T
1
(rope 1)
1.
IV
2.
II
3.
I
4.
correct
Explanation:
003 (part 3 of 7) 2.0 points
What is the
y
component oF the gravitational
Force acting on the block? (A component can
be positive or negative.) Use
g
= 9
.
8 m
/
s
2
.
Correct answer:

441 N.
Explanation:
Since gravity only acts along the
y
axis (in
our coordinate system), we can write
F
grav
,y
=
F
grav
=

m g
=

(45 kg)(9
.
8 m
/
s
2
)
=

441 N
.
004 (part 4 of 7) 3.0 points
What is the
y
component oF the Force on the
block due to rope 2?
Correct answer: 441 N.
Explanation:
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View Full Documentmadrid (tmm2353) – HW 51 – Antoniewicz – (56445)
2
Since we’ve already found the force due to
gravity acting downward on the box, this part
is pretty simple. The box is not in motion,
so the upward force must exactly balance the
downward force. So the answer here is the
same as for part 3, just with the opposite
sign.
005 (part 5 of 7) 4.0 points
What is the magnitude of
v
F
T
2
?
Correct answer: 552
.
192 N.
Explanation:
Since we know the value of the
y
component
of
v
F
T
2
, Fnding the magnitude of the total
tension in rope 2 is just trigonometry:
v
v
v
v
F
T
2
v
v
v
cos 37
◦
= 441 N
⇒
v
v
v
v
F
T
2
v
v
v
=
441 N
cos 37
◦
=
552
.
192 N
.
006 (part 6 of 7) 4.0 points
What is the
x
component of the force on the
block due to rope 2?
Correct answer: 332
.
317 N.
Explanation:
We use trigonometry again:
F
T
2
,x
=
v
v
v
v
F
T
2
v
v
v
sin37
◦
= (552
.
192 N) sin37
◦
=
332
.
317 N
.
007 (part 7 of 7) 3.0 points
What is the
x
component of the force on the
block due to rope 1?
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 Fall '08
 Turner
 Force, Correct Answer

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