Exam
Name___________________________________
MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question.
1) A cylindrical rod of length 1 m and radius 1 cm is submerged in water. The rod has a
1)
non-uniform mass distribution such that one half of the rod is much more massive than
the other half. At which point in the rod can the entire buoyant force be considered to be
acting?
A) At the rod's center of mass
B) None of these
C) At the rod's center of gravity
D) Two of the given choices are correct
E) At the rod's geometrical center
2) A rock is suspended from a scale reads 20.0 N. A beaker of water (having a density of
1000 kg/m3) is raised up so the rock is totally submerged in the water. The scale now
reads 12.5 N. What is the density of the rock?
A) 2.50 × 103 kg/m3
B) 2.33 × 103 kg/m3
C) 3.00 × 103 kg/m3
D) 2.67 × 103 kg/m3
E) 1.60 × 103 kg/m3
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2)
3) A wheel has a radius of 0.40 m and is mounted on frictionless bearings. A block is
suspended from a rope that is wound on the wheel and attached to it (see figure). The
wheel is released from rest and the block descends 1.5 m in 2.00 s without any slipping
of the rope. The tension in the rope during the descent of the block is 20 N. What is the
moment of inertia of the wheel?
A) 3.9 kg • m2
B) 3.5 kg • m2
C) 4.1 kg • m2
D) 4.3 kg • m2
E) 3.7 kg • m2
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3)
4) A climber with a weight of 533.8 N is held by a belay rope connected to her climbing
4)
harness and belay device; the force of the rope on her has a line of action through her
center of mass. The indicated angles are =56.0° and =30.0 °. If her feet are on the
verge of sliding on the vertical wall, what is the coefficient of static friction between her
climbing shoes and the wall?
A) 1.05
B) 0.84
C) None of these
D) 0.67
E) 1.20
5)
As the speed of a horizontally moving fluid increases, the pressure in the fluid
A) decreases.
B) increases.
C) remains constant.
D) may increase or decrease, depending on the density of the fluid.
5)
6)
Tensile strain is
A) the stress per unit area.
B) the ratio of the change in length to the original length.
C) the same as force.
D) None of these
E) the applied force per cross-sectional area.
6)
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7) A ping-pong ball sits inside a funnel as shown. The bottom of the funnel is
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connected to a pump which can send a fast-moving jet of air (velocity of 10 m/s)
through it. What happens to the ball when the pump is turned on?
A) The ball will rise to a height somewhat higher than 5.10 m as lift forces
predicted by Bernoulli's equation will exceed the air resistance forces.
B) The ball will never take off because of a low-pressure region developing in the
narrow gap beween the ball and the funnel wall.
C) The ball will rise to a height somewhat lower than 5.10 m as air resistance
forces will be greater than the lift forces predicted by Bernoulli's equation.
D) The ball will rise to a height of 5.10 m
E) The ball will never take off because of viscous effects along the funnel wall and
around the surface of the ball
8) A horizontal tube consists of a 7.0-cm diameter pipe that narrows to a 2.0-cm-diameter
throat. In the pipe, the water pressure is twice atmospheric pressure and the water flows
with a speed of 0.40 m/s. What is the pressure in the throat, assuming that the water
behaves like an ideal fluid? The density of water is 1000 kg/m3, and atmospheric
pressure is 1 atm = 1.01 × 105 Pa.
A)
2.0 atm
B) 0.12
C)
atm
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1.9 atm
D)
2.1 atm
8)
9) Consider a uniform solid sphere of radius R and mass M rolling without slipping.
9)
Which form of its kinetic energy is larger, translational or rotational?
A) Both forms of energy are equal.
B) Its translational kinetic energy is larger than its rotational kinetic energy.
C) Its rotational kinetic energy is larger than its translational kinetic energy.
D) You need to know the speed of the sphere to tell.
10) An 82.0 kg-diver stands at the edge of a light 5.00-m diving board, which is supported
10)
by two narrow pillars 1.60 m apart, as shown in the figure. Find the magnitude and
direction of the force exerted on the diving board by pillar A.
A)
1.71 kN downwards
B) 1.71 kN upwards
C) 803 N downwards
D) None of these
E) 803 N upwards
11) A rock is under water in a shallow lake. Assume that water is an incompressible fluid
with a constant density. As the rock sinks deeper and deeper into water, the buoyant
force on it
A) remains constant.
B) decreases.
C) increases.
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11)
12) A ball is released from rest on a no-slip surface, as shown in the figure. After reaching
12)
its lowest point, the ball begins to rise again, this time on a frictionless surface as
shown in the figure. When the ball reaches its maximum height on the frictionless
surface, it is
A)
at a greater height than when it was released.
B) at the same height than when it was released.
C) at a lesser height than when it was released.
D) It is impossible to tell without knowing the mass of the ball.
E) It is impossible to tell without knowing the radius of the ball.
13) The cylinder shown is rolling without slipping as a force of 50 N is applied to the
end of the rope. Calculate the magnitude of the acceleration of the center of mass
of the cylinder . Assume that the cylinder has a mass of 5.00 kg and a
non-uniform mass distribution such that its rotational inertia (about an axis
through its center of mass and perpendicular to its flat surfaces) is (1/4)MR2,
where M and R are its mass and radius respectively.
A) 10.0 m/s2
B) 16.0 m/s2
C) None of these
D) 13.3 m/s2
E) 30.0 m/s2
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13)
14) A tire is rolling along a road, without slipping, with a velocity v. A piece of tape is
14)
attached to the tire. When the tape is opposite the road (at the top of the tire), its
velocity with respect to the road is
A) 2v.
B) zero.
C) v.
D) 1.5v.
E) The velocity depends on the radius of the tire.
15) What
A)
version is this test? Please enter "A" on the scantron.
B)
C)
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D)
15)
Answer Key
Testname: TEST3_V0
1) E
2) D
3) D
4) D
5) A
6) B
7) B
8) C
9) B
10) A
11) A
12) C
13) B
14) A
15) A
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