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A packing crate slides down an inclined ramp at constant velocity. Thus we
can deduce that
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a
frictional force is acting on it.
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a
net force is acting on it.
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it
may be accelerating.
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Gravity
is not acting on it.
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You fall while skiing and one ski (of weight W) loosens and slides down an
icy slope (assume no friction), which makes an angle q with the horizontal.
The force that pushes it down along the hill is
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zero;
it moves with constant velocity.
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W
cos q
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W
sin q
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it
is not acted on by a gravitational force.
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A rope, tied between a motor and a crate, can pull the crate up a hill of
ice (assume no friction) at constant velocity. The free-body diagram of the
crate should contain
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one
force.
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two
forces.
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three
forces.
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four
forces.
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If two identical masses, attached by a massless cord passing over a massless,
frictionless pulley of an Atwood's machine (at different heights), are
released
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the
lower mass will go down.
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the
higher mass will go down.
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the
masses will not move.
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the
motion will depend on the actual value of each mass.
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The same horizontal force is applied to objects of different mass. Which
of the following graphs illustrates the experimental results?
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 A
train consists of a caboose (mass = 1000 kg), a car (mass 2000 kg), and an
engine car (mass 2000 kg). If the train has an acceleration of 5 m/s2,
then the tension force in the coupling between the middle car and the engine
car is
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25,000
N
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20,000
N
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15,000
N
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10,000
N
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A decoration, of mass M, is suspended by a string from the ceiling inside
an elevator. The elevator is traveling upward with a constant speed. The
tension in the string is
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equal
to Mg.
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less
than Mg.
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greater
than Mg.
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impossible
to tell without knowing the speed.
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Two identical masses are attached by a light string that passes over a
small pulley, as shown. The table and the pulley are frictionless. The system
is moving
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with
an acceleration less than g.
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with
an acceleration equal to g.
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with
an acceleration greater than g.
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at
constant speed.
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 Two
cardboard boxes full of books are in contact with each other on a
frictionless table. Box H has twice the mass of box G. If you push on box G
with a horizontal force F, then box H will experience a net force of
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2/3
F
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F
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3/2
F
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2
F
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 A
toolbox, of mass M, is resting on a flat board. One end of the board is
lifted up until the toolbox just starts to slide. The angle theta that the
board makes with the horizontal for this to occur depends on the
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mass,
M.
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Gravity
is not acting on it.
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normal
force.
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coefficient
of static friction, mu.
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Four students perform an experiment by pulling an object horizontally
across a frictionless table. They repeat the experiment on several other
objects of different masses, always applying just enough force to produce the
same acceleration. They each graph the results, individually. Which student's
graph is correct?
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An object is placed on an inclined plane. The angle of incline is
gradually increased until the object begins to slide. The angle at which this
occurs is q. What is the coefficient of static friction between the object
and the plane?
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sin
q
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cos
q
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tan
q
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Cannot
determine without knowing the mass of the object.
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A mass on a string attached to a ceiling is pulled to the side and let go.
When the string makes an angle q with the vertical, which of the following is
not true?
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The
weight is down.
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The
tension equals mg*cos(q).
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The
tension equals mg*sin(q).
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The
tension and the weight are never in the same direction.
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A roller coaster car does a loop-the-loop. When it is upside down at the
very top, which of the following is true?
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The
normal force and the weight are in opposite directions.
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The
normal force and the weight are perpendicular to each other.
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The
weight is zero.
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The
normal force and the weight are in the same direction.
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A roller coaster car does a loop-the-loop. When it is right-side up at the
very bottom, which of the following is true?
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The
normal force and the weight are in opposite directions.
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The
normal force and the weight are perpendicular.
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The
weight is zero.
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The
normal force and the weight are in the same direction.
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A 2 kg box sits on a 3 kg box which sits on a 5 kg box. The 5 kg box rests
on a table top. What is the normal force exerted on the 5 kg box by the table
top?
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19.6
N
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29.4
N
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49
N
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98
N
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A 2 kg box sits on a 3 kg box which sits on a 5 kg box. The 5 kg box rests
on a table top. What is the normal force exerted by the 5 kg box on the 3 kg
box?
|
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|
19.6
N
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|
29.4
N
|
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49
N
|
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98
N
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A 5 kg (4.9 N) book rests on your desk. Which of the following answers is not
correct?
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The
normal force on the book equals its weight because of Newton's First Law.
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The
normal force on the book equals its weight because of Newton's Second Law.
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The
normal force on the book equals the weight because of Newton's Third Law.
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A 5 kg (4.9 N) book rests on your desk. What is the reaction force to the
4.9 N weight (force) of the book?
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The
4.9 N normal force from the table on the book.
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The
4.9 N reaction force from the book on the table.
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The
weight of the earth.
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A
4.9 N force on the Earth.
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You stand on a bathroom scale in an elevator accelerating upwards and it
reads 200 Newtons. Which of the following is true?
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You
weigh 200 Newtons.
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The
scale exert a 200 N force on you.
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The
acceleration of the elevator is 20.4 m/s^2.
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None
of the above are correct.
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During the investigation of a traffic accident, police find skid marks 90
m long. They determine the coefficient of friction between the car's tires
and the roadway to be 0.5 for the prevailing conditions. To find the speed of
the car you must
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know
the mass of the car.
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find
the acceleration of the car.
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know
the mass of the car and find the acceleration of the car.
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An object moves left to right (right is positive) with speed decreasing at
a constant rate and
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its
acceleration is positive.
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|
the
net force on it is decreasing.
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the
net force on it is increasing.
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its
acceleration is negative.
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Money is to wealth as
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|
weight
is to (the force of) gravity.
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weight
is to mass.
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mass
is to inertia.
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gravity
is to mass.
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A car pulls on a rope tied to a tree with a force of 1000 Newtons. Which
of the following is not true.
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|
The
rope pulls on the tree with a force of 1000 Newtons.
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The
tree pulls on the rope with a force of 1000 Newtons.
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|
The
tension in the rope is 2000 Newtons.
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The
tension in the rope is 1000 Newtons.
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A 5 kg block and a 10 kg block slide down a frictionless incline and
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they
both have the same acceleration.
|
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|
the
5 kg block has an acceleration of twice that of the 10 kg block.
|
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|
the
10 kg block has an acceleration of twice that of the 5 kg block.
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|
their
acceleration depends on the normal force.
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