Version 008/AAACA – QTest #5 – Antoniewicz – (56445)
1
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printout
should
have
3
questions.
Multiplechoice questions may continue on
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before answering.
001
10.0 points
A 4 kg metal block slides along the floor.
The coe
ffi
cient of sliding (or kinetic) friction
between the block and the floor is 0
.
64. The
initial speed of the block is 6 m
/
s.
How far
does the block slide before coming to a stop?
1. 2.8699
2. 3.90795
3. 2.7414
4. 5.10204
5. 15.3061
6. 5.92495
7. 4.47984
8. 7.65306
9. 9.66702
10. 4.96415
Correct answer: 2
.
8699.
Explanation:
Let :
m
= 4 kg
,
g
= 9
.
8 m
/
s
2
,
v
i
= 6 m
/
s
,
and
μ
k
= 0
.
64
.
We know that the frictional force
f
k
is given
by

μ
k
F
N
where
F
N
is the normal force and
equal to
mg
. Thus, we make use of the rela
tion
v
f
=
v
i
+
f
k
m
Δ
t
=
v
i

μ
k
(
mg
)
m
Δ
t
But, the final velocity is zero since the block
comes to a stop.
0 = 6 m
/
s

(0
.
64)(9
.
8 m
/
s
2
)
Δ
t
Δ
t
= 0
.
956633 s
The distance covered is given by
x
f
=
x
i
+
v
i
Δ
t
+
f
k
2
m
Δ
t
2
=
x
i
+
v
i
Δ
t

μ
k
(
mg
)
2
m
Δ
t
2
= 0 + (6 m
/
s)(0
.
956633 s)

(0
.
64)(9
.
8 m
/
s
2
)
2
(0
.
956633 s
= 2
.
8699
002
10.0 points
L
b
Mg
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 Fall '08
 Turner
 Force, ax, Iiia

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