Version 129/ACAAB – inclasstest 04 – turner – (57340)
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001
10.0points
A spring with a springconstant 2
.
5 N
/
cm
is compressed 28 cm and released. The 6 kg
mass skids down the frictional incline of height
38 cm and inclined at a 18
◦
angle.
The acceleration of gravity is 9
.
8 m
/
s
2
.
The path is frictionless except for a dis
tance of 0
.
8 m along the incline which has a
coefficient of friction of 0
.
2
.
6 kg
18
◦
μ
= 0
.
2
0
.
8 m
38 cm
28 cm
k
= 2
.
5 N
/
cm
v
f
Figure:
Not drawn to scale.
What is the final velocity
v
f
of the mass?
1. 2.59615
2. 2.68401
3. 2.78068
4. 2.93581
5. 2.96869
6. 3.25356
7. 4.39476
8. 2.13813
9. 2.1074
10. 3.65871
Correct answer: 2
.
78068 m
/
s.
Explanation:
Let :
g
= 9
.
8 m
/
s
2
=
,
k
= 2
.
5 N
/
cm = 250 N
/
m
,
x
= 28 cm = 0
.
28 m
,
μ
= 0
.
2
,
ℓ
= 0
.
8 m
,
h
= 0
.
38 m
,
m
= 6 kg
,
and
θ
= 18
◦
,
Consider the kinetic energy of the mass.
The mass receives its initial kinetic energy
from the potential energy of the spring
K
i
=
U
spring
=
1
2
k x
2
(1)
=
1
2
(250 N
/
m) (0
.
28 m)
2
= 9
.
8 J
.
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 Spring '08
 Turner
 Physics, Energy, Kinetic Energy, Potential Energy, 1 K, 1 m, 2 1 m

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