1. A book is sitting on the very slick (frictionless) passenger seat of a car.
The car is moving at
a constant velocity.
The driver suddenly hits his breaks.
The book suddenly slides off the seat.
Why?
(a)
A force acted on the book in the forward direction.
(b)
A force acted on the book in the backward direction.
(c)
A force acted on the car and the book in the forward direction.
(d)
A force acted on the car and the book in the backward direction.
(e)
No force acted on the book, so it continued to move at the same original velocity while the car
slowed down.
4. A sled is being pulled across a horizontal surface at a
constant velocity
.
The pulling
force is given by F
A
and is directed at an angle
above the horizontal.
What is the correct freebody diagram for the
sled?
Read the force labels carefully!
(a)
F
N
F
A
f
s
W
F
N
F
A
f
k
W
F
N
F
A
f
k
W
(b)
(c)
F
N
F
A
W
f
s
(d)
F
N
F
A
f
k
W
(e)
2. A ball moves with a constant speed of 4 m/s around a circle of radius 0.25 m.
What is the
period of the rotation?
(a) 0.1 s
(b) 0.4 s
(c) 0.7 s
(d) 8 s
(e) 2 s
3. An object is lifted vertically 6 meters and then returned to its original position.
What was
the work done on the object by gravity during the round trip if the object weighs 20 N?
a) No work is done on the object
b) 60 J
c) 120 J
d) 240 J
e) 120 J
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View Full Document5. Two objects (3 kg and 9 kg) are released simultaneously on a frictionless
inclined plane
that makes an angle of 35
o
with the horizontal.
What can we say about their accelerations
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 Spring '08
 Online
 Force, Friction, Normal Force, kg object

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