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Phys 298
Brown
Exam 1
Name ______________________________
Friday, February 8, 2008
This is a closedbook, closednote, closedneighbor exam.
You are allowed one 3”x5”
card with information, a calculator (not a computer), and your writing instruments.
Multiple choice questions each have only one correct choice.
Partial credit will be given
on the ‘workout’ problems.
You may use the value
g
= 10 m/s
2
where needed.
Good luck, and “May the Net Force be with you!”
1.
An eccentric Physics professor sits in an airplane holding an unwound yoyo such
that it hangs straight down.
As the plane accelerates down the runway toward
takeoff, the professor notices that the yoyo string makes an angle
θ
with the
vertical.
What is the acceleration of the airplane? (Yes, I really did this once,
traveling with a student to a research conference).
a.
g
cos
"
b.
g
sin
c.
g
tan
d.
g
e.
0
F
x
=
T
sin
=
ma
F
y
=
T
cos
#
mg
=
0
$
T
cos
=
mg
%
%
T
sin
T
cos
=
ma
mg
$
a
=
g
tan
2.
An object is moving
a.
There is a net force on the object in the direction of motion.
b.
There is a net force on the object in the direction opposite motion.
c.
No forces act on the object.
d.
Not enough information is given to comment on forces on the object.
3.
An object is initially moving in the positive xdirection with speed
v
0
.
It is acted
on
for a time
t
by a net force in the negative ydirection.
At the end of this time,
what is the xcomponent of velocity?
a.
v
0
b.
greater than
v
0
c.
less than
v
0
, but greater than 0.
d.
0
e.
negative
First, a moving object doesn’t HAVE to have a force acting on it – that’s an old
Aristotelian idea.
Second, we don’t know HOW the object is moving.
Answer:
d
A force in the ydirection doesn’t affect motion in the xdirection.
Answer:
a
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The motions of a car and a truck along a straight road are represented by the
velocitytime graphs below.
The two vehicles are initially alongside each other at
time
t = 0.
At time
T
, what is true of the distances traveled by the vehicles since
time
t = 0
?
a.
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This note was uploaded on 05/15/2008 for the course PHYS 298 taught by Professor Morrison during the Spring '08 term at University of Louisville.
 Spring '08
 Morrison

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