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001
10.0 points
Potential energy and kinetic energy are forms
of what kind of energy?
1.
heat
2.
chemical
3.
mechanical
correct
4.
nuclear
5.
electromagnetic
Explanation:
002
(part 1 of 2) 10.0 points
If a golf ball and a pingpong ball both move
with the same kinetic energy, which has the
greater speed?
1.
the golf ball
2.
Cannot be determined
3.
The two balls have the same speed.
4.
the pingpong ball
correct
Explanation:
Kinetic energy is
1
2
m v
2
.
Since they have
the same kinetic energy,
1
2
m
g
v
2
g
=
1
2
m
p

p
v
2
p

p
.
Since
m
g
> m
p

p
, it follows that
v
g
< v
p

p
.
003
(part 2 of 2) 10.0 points
In a gaseous mixture of massive molecules
and light molecules with the same average
KE, which have the greater speed?
1.
They have the same speed.
2.
the massive molecules
3.
the light molecules
correct
4.
Cannot be determined
Explanation:
Since
m
massive
> m
light
, v
massive
< v
light
.
004
10.0 points
Does the KE of a car change more when it
accelerates from 27 km
/
h to 37 km
/
h or when
it accelerates from 37 km
/
h to 47 km
/
h?
1.
More information is needed.
2.
From 37 km
/
h to 47 km
/
h
correct
3.
No di
ff
erence
4.
From 27 km
/
h to 37 km
/
h
Explanation:
The change in kinetic energy is
1
2
m v
2
f

1
2
m v
2
i
,
so we are comparing
v
2
f

v
2
i
.
(47 km
/
h)
2

(37 km
/
h)
2
= 840 km
2
/
h
2
is larger than
(37 km
/
h)
2

(27 km
/
h)
2
= 640 km
2
/
h
2
,
so KE changes more for a given
Δ
v
at the
higher speeds.
005
(part 1 of 5) 10.0 points
A 15
.
7 kg block is dragged over a rough, hor
izontal surface by a constant force of 148 N
acting at an angle of angle 34
.
1
◦
above the
horizontal.
The block is displaced 75
.
8 m,
and the coe
ffi
cient of kinetic friction is 0
.
194.
15
.
7 kg
μ
= 0
.
194
148 N
34
.
1
◦
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Find the work done by the 148 N force. The
acceleration of gravity is 9
.
8 m
/
s
2
.
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 Spring '08
 Jones,S
 Physics, Energy, Force, Kinetic Energy, Potential Energy, Heat, Correct Answer, Wnet

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