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Mueller/Saab
PHY2048
Exam 1
September 29, 2009
1.
Two girders are made of the same material. Girder A is twice as long as girder B and
has a crosssectional area that is twice as great. The ratio of the mass density of girder A
to the mass density of girder B is:
(1) 1
(2) 2
(3) 4
(4) 1/2
(5) 1/4
2.
A particle moves along the x axis from x
i
to x
f
. Of the following values of the initial
and final coordinates, which results in the displacement with the largest magnitude?
(1)
x
i
= 4 m, x
f
= 4 m
(2)
x
i
= 4 m, x
f
= 6 m
(3)
x
i
= 4 m, x
f
= 8 m
(4)
x
i
= 4 m, x
f
= 2 m
(5)
x
i
= 4 m, x
f
= 2 m
3.
A car travels 40 kilometers at a constant speed of 80 km/h and then travels 60
kilometers at a constant speed of 40 km/h. The average speed of the car for this 100km
trip is:
(1) 50 km/h
(2) 45 km/h
(3) 55 km/h
(4) 60 km/h
(5) 65 km/h
4.
Which of the above five graphs of position, x, versus time, t, represents the motion of
an object whose speed is increasing with time?
(1)
A
(2)
B
(3)
C
(4)
D
(5)
E
5.
A drag racing car starts from rest at t = 0 and moves along a straight line with velocity,
v, that varies with time, t, according to v(t) = bt
2
, where b is a constant. The expression
for the distance, x, traveled by this car from its position at t = 0 is:
(1) bt
3
/3
(2)
bt
3
(3) 3bt
3
(4) 2bt
(5) bt
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6. If
B
A
B
A
r
r
r
r
+
=

and neither
A
r
nor
B
r
vanish, then:
(1)
A
r
and
B
r
are parallel and in opposite directions
(2)
A
r
and
B
r
are parallel and in the same direction
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 Fall '08
 Field
 Physics, Friction, Mass, Kilogram, constant speed

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