### Surface Tension – Physics chapters 2 Quiz

The key terms of Physics Chapter 2 Quiz include, Surface tension, Moment of inertia, Density, Solid sphere, total kinetic energy, spherical particles, unit of viscosity, Reynolds number, angular acceleration, centipoise, angular speed.

Water is being sprayed from a nozzle at the end of a garden hose of diameter 2.0 cm. If the
nozzle has an opening of diameter 0.50 cm, and if the water leaves the nozzle
at a speed of 10 m/s, what is the speed of the water inside the hose?
a. 0.63 m/s – correct
b. 0.80 m/s
c. 2.5 m/s
d. also 10 m/s

A unit for viscosity, the centipoise, is equal to which of the following?
a. 10-3 N·s/m2 – correct
b. 10-2 N·s/m2
c. 10-1 N·s/m2
d. 102
N·s/m2

The condition for onset of turbulent flow is that the Reynolds Number
reaches what value?
a. 1 000
b. 2 000
c. 3 000 – correct
d. 4 000

A fluid has a density of 1 040 kg/m3. If it rises to a height of 1.8 cm in a 1.0-mm diameter
capillary tube, what is the surface tension of the liquid? Assume a contact angle of zero.
a. 0.046 N/m – correct
b. 0.056 N/m
c. 0.092 N/m

A pipe carrying water has a radius of 1.0 cm. If the flow velocity is 9.0
cm/s, which of the
following characterizes the flow? Take the viscosity of water to be 1.0 × 10-3
N·s/m.
a. streamlined – correct
b. unstable
c. turbulent
d. stagnant

In order to overcome a surface tension of a fluid, a force of 1.32 × 10-2 N is required to lift a
wire ring of circumference 12.0 cm. What is the surface tension of the fluid?
a. 0.055 N/m – correct
b. 0.11 N/m
c. 0.035 N/m
d. 0.018 N/m

A pipe of diameter three cm is replaced by one of the same length but of diameter six cm. If
the pressure difference between the ends of the pipe remains the same, by what
factor is the rate of flow of a viscous liquid through it changed?
a. 2
b. 4
c. 8
d. 16 – correct

Spherical particles of density 2.0 g/cm3
are shaken in a container of water (viscosity = 1.0 ×
10-3 N·s/m3). The water is 8.0 cm deep and is allowed to stand for 30 minutes. What is the
greatest terminal velocity of the particles still in suspension at that time?
a. 0.55 × 10-5 m/s
b 1.1 × 10-5 m/s
c. 2.2 × 10-5 m/s
d. 4.4 × 10-5 m/s – correct

Spherical particles of density 2.0 g/cm3 are shaken in a container of water (viscosity = 1.0 ×
10-3 N·s/m3). The water is 8.0 cm deep and is allowed to stand for 30 minutes. What is the
radius of the largest particles still in suspension at that time?
a. 4.5 × 10-6 m – correct
b. 9.0 × 10-6 m
c. 2.3 × 10-6 m
d. 5.6 × 10-6 m

A centrifuge rotates at 100 rev/s (i.e., 628 rad/s). If the test tube places
the suspension at 8.0
cm from the axis of rotation, by what factor are the terminal speeds of the
settling particles
increased as compared to sedimentation cause by gravity?
a. 3.2 × 102 – correct
b. 64
c. 800
d. 3.9 × 105

78. Which of the following characterizes the net force on a particle falling
through a fluid at its
terminal speed?
a. It is at a maximum.
b. It is upwards.
c. It is downwards.
d. It is zero. – correct

A vault is opened by applying a force of 300 N perpendicular to the plane of
the door, 0.80 m
from the hinges. Find the torque due to this force about an axis through the
hinges.
a. 120 N⋅m
b. 240 N⋅m – correct
c. 300 N⋅m
d. 360 N⋅m

A 3.0-m rod is pivoted about its left
end. A force of 6.0 N is applied perpendicular to the rod
at a distance of 1.2 m from the pivot causing a ccw torque, and a force of 5.2
N is applied at
the end of the rod 3.0 m from the pivot. The 5.2 N is at an angle of 30o
to the rod and causes a
cw torque. What is the net torque about the pivot?
a. 15 N·m
b. 0 N·m
c. -6.3 N·m
d. -0.6 N·m – correct

A rod of length L is pivoted about its left end and has a force F applied
perpendicular to the
other end. The force F is now removed and another force F’ is applied at the
midpoint of the
rod. If F’ is at an angle of 30°
with respect to the rod, what is its magnitude if the resulting
torque is the same as when F was applied?
a. F
b. 2F
c. 3F
d. 4F – correct

Two children seat themselves on a
seesaw. The one on the left has a weight of 400 N while
the one on the right weighs 300 N. The fulcrum is at the midpoint of the
seesaw. If the child
on the left is not at the end but is 1.50 m from the fulcrum and the seesaw is
balanced, what is
the torque provided by the weight of the child on the right?
a. 600 N·m
b. 450 N·m
c. -600 N·m – correct
d. -450 N·m

A bucket filled with water has a mass of 23 kg and is attached to a rope,
which in turn, is wound around a 0.050-m radius cylinder at the top of a well. What torque does
the weight of water and bucket produce on the cylinder if the cylinder is not permitted to rotate? (g = 9.8m/s2)
a. 34 N⋅m
b. 17 N⋅m
c. 11 N⋅m – correct
d. 23 N⋅m

A bucket of water with total mass 23 kg is attached to a rope, which in turn, is wound around
a 0.050-m radius cylinder at the top of a well. A crank with a turning radius of 0.25 m is
attached to the end of the cylinder. What minimum force directed perpendicular to the crank
handle is required to just raise the bucket? (Assume the rope’s mass is negligible, that
cylinder turns on frictionless bearings, and that g = 9.8 m/s2.)
a. 45 N – correct
b. 68 N
c. 90 N
d. 135 N

A uniform bridge span weighs 50.0 × 103
N and is 40.0 m long. An automobile weighing
15.0 × 103
N is parked with its center of gravity located 12.0 m from the right pier. What
upward support force does the left pier provide?
a. 29.5 × 103 N – correct
b. 35.5 × 103
N
c. 65.0 × 103 N
d. 32.5 × 103
N

Masses are distributed in the x,y-plane as follows: 6.0 kg at (0.0, 0.0) m,
4.0 kg at (2.0, 0.0)
m, and 5.0 kg at (2.0, 3.0) m. What is the x-coordinate of the center of
gravity of this system
of masses?
a. 18 m
b. 2.0 m
c. 1.2 m – correct
d. 1.0 m

Masses are distributed in the
xy-plane as follows: 10 kg at (2.0, 6.0) m, 4.0 kg at (2.0, 0.0) m,
and 6.0 kg at (0.0, 3.0) m. Where would a 20-kg mass need to be positioned so
that the center
of gravity of the resulting four mass system would be at the origin?
a. (1.4, 3.9) m
b. (3.9, 1.4) m
c. (-1.4, -3.9) m – correct
d. (-3.9, -1.4) m

A hoop of radius 1.0 m is placed in the first quadrant of an xy-coordinate
system with its rim
touching both the x-axis and the y-axis. What are the coordinates of its center
of gravity?
a. (1.0, 1.0) m – correct
b. (0.7, 0.7) m
c. (0.5, 0.5) m
d. Since there is nothing at the center of the hoop, it has no center of
gravity.

. Tasha has mass 20 kg and wants to use a 4.0-m board of mass 10 kg as a
seesaw. Her friends
are busy, so Tasha seesaws by herself by putting the support at the system’s
center of gravity
when she sits on one end of the board. How far is she from the support point?
a. 2.0 m
b. 1.0 m
c. 0.67 m – correct
d. 0.33 m

In order to overcome a surface tension of a fluid, a force of 1.32 × 10-2 N is required to lift a
wire ring of circumference 12.0 cm. What is the surface tension of the fluid?
a. 0.055 N/m – correct
b. 0.11 N/m
c. 0.035 N/m
d. 0.018 N/m

An 80-kg man is one fourth of the way up a 10-m ladder that is resting
against a smooth,
frictionless wall. If the ladder has a mass of 20 kg and it makes an angle of
60° with the
ground, find the force of friction of the ground on the foot of the ladder.
a. 7.8 x 102
N
b. 2.0 x 102
N
c. 50 N
d. 1.7 x 102 N – correct

A 100-N uniform ladder, 8.0 m long, rests against a smooth vertical wall.
The coefficient of
static friction between ladder and floor is 0.40. What minimum angle can the
with the floor before it slips?
a. 22°
b. 51° – correct
c. 18°
d. 42°

4. A meter stick is supported by a knife-edge at the 50-cm mark. Doug hangs
masses of 0.40
and 0.60 kg from the 20-cm and 80-cm marks, respectively. Where should Doug
hang a third
mass of 0.30 kg to keep the stick balanced?
a. 20 cm
b. 70 cm
c. 30 cm – correct
d. 25 cm

An 800-N billboard worker stands on a 4.0-m scaffold supported by vertical
ropes at each
end. If the scaffold weighs 500 N and the worker stands 1.0 m from one end,
what is the
tension in the rope nearest the worker?
a. 450 N
b. 500 N
c. 800 N
d. 850 N – correct

An 800-N billboard worker stands on a
4.0-m scaffold weighing 500 N and supported by
vertical ropes at each end. How far would the worker stand from one of the
supporting ropes
to produce a tension of 550 N in that rope?
a. 1.4 m
b. 2.0 m
c. 2.5 m – correct
d. 2.7 m

. A woman who weighs 500 N stands on an 8.0-m-long board that weighs 100 N.
The board is
supported at each end. The support force at the right end is 3 times the
support force at the
left end. How far from the right end is the woman standing?
a. 4.0 m
b. 2.0 m
c. 2.7 m
d. 1.6 m – correct

A uniform, horizontal beam of length 6.0 m and weight 120 N is attached at
one end to a wall
by a pin connection (so that it may rotate). A cable attached to the wall above
the pin
supports the opposite end. The cable makes an angle of 60° with the horizontal.
What is the
tension in the cable needed to maintain the beam in equilibrium?
a. 35 N
b. 69 N – correct
c. 60 N
d. 120 N

A uniform 1.0-N meter stick is
suspended horizontally by vertical strings attached at each
end. A 2.0-N weight is suspended from the 10-cm position on the stick, another
2.0-N weight
is suspended from the 50 cm position, and a 3.0-N weight is suspended from the
60 cm
position. What is the tension in the string attached at the 100-cm end of the
stick?
a. 1.9 N
b. 3.0 N
c. 3.5 N – correct
d. 4.0 N

The quantity “moment of
inertia” (in terms of the fundamental quantities of mass, length, and
time) is equivalent to:
a. ML2
T−2
.
b. ML.
c. ML2 – correct
.
d. ML−1
T−2
.

. A 4.2-kg mass is placed at (3.0, 4.0) m. Where can an 8.4-kg mass be
placed so that the
moment of inertia about the z-axis is zero?
a. (-3.0, -4.0) m
b. (-6.0, -8.0) m
c. (-1.5, -2.0) m
d. There is no position giving this result. – correct

A 4.0-kg mass is placed at (3.0, 4.0) m, and a 6.0-kg mass is placed at
(3.0, -4.0) m. What is
the moment of inertia of this system of masses about the x-axis?
a. 160 kg·m2 – correct
b. 90 kg·m2
c. 250 kg·m2
d. 32 kg·m2

A 4.0-kg mass is placed at (3.0, 4.0) m, and a 6.0-kg mass is placed at
(3.0, -4.0) m. What is
the moment of inertia of this system of masses about the y-axis?
a. 160 kg·m2
b. 90 kg·m2 – correct
c. 250 kg·m2
d. 180 kg·m2

In order to overcome a surface tension of a fluid, a force of 1.32 × 10-2 N is required to lift a
wire ring of circumference 12.0 cm. What is the surface tension of the fluid?
a. 0.055 N/m – correct
b. 0.11 N/m
c. 0.035 N/m
d. 0.018 N/m

A 4.0-kg mass is placed at (3.0, 4.0)
m, and a 6.0-kg mass is placed at (3.0, -4.0) m. What is
the moment of inertia of this system of masses about the z-axis?
a. 160 kg·m2
b. 90 kg·m2
c. 250kg·m2 – correct
d. 180 kg·m2

If a net torque is applied to an object, that object will experience:
a. a constant angular speed.
b. an angular acceleration. – correct
c. a constant moment of inertia.
d. an increasing moment of inertia.

According to Newton’s second law, the
angular acceleration experienced by an object is
directly proportional to:
a. its moment of inertia.
b. the net applied torque. – correct
c. the object’s size.
d. choices a and b above are both valid.

A ventilation fan with a moment of
inertia of 0.034 kg⋅m2
has a net torque of 0.11 N⋅m
applied to it. What angular acceleration does it experience?

A disk has a moment of inertia of 3.0
× 10−4
kg⋅m2
and rotates with an angular speed of 3.5
rad/sec. What net torque must be applied to bring it to rest within 3 s?
a. 4.5 × 10−3 N⋅m
b. 7.5 × 10−4 N⋅m
c. 3.5 × 10−4 N⋅m – correct
d. 5.0 × 10−4 N⋅m

The Earth moves about the Sun in an
elliptical orbit. As the Earth moves closer to the Sun,
which of the following best describes the Earth-Sun system’s moment of inertia?
a. decreases – correct
b. increases
c. remains constant
d. none of the above choices are valid

A bowling ball has a mass of 7.0 kg, a moment of inertia of 2.8 × 10−2
kg⋅m2
0.10 m. If it rolls down the lane without slipping at a linear speed of 4.0
m/s, what is its
angular speed?

In order to overcome a surface tension of a fluid, a force of 1.32 × 10-2 N is required to lift a
wire ring of circumference 12.0 cm. What is the surface tension of the fluid?
a. 0.055 N/m – correct
b. 0.11 N/m
c. 0.035 N/m
d. 0.018 N/m

A baseball pitcher, loosening up his arm before a game, tosses a 0.15-kg
ball using only the
rotation of his forearm, 0.32 m in length, to accelerate the ball. If the ball
starts at rest and is
released with a speed of 12 m/s in a time of 0.40 s, what is the average
angular acceleration of
the arm and ball?

A baseball pitcher loosens up his pitching arm. He tosses a 0.15-kg ball
using only the
rotation of his forearm, 0.32 m in length, to accelerate the ball. What is the
moment of inertia
of the ball alone as it moves in a circular arc with a radius of 0.32 m?
a. 1.5 × 10−2 kg⋅m2 – correct
b. 16 × 10−2 kg⋅m2
c. 4.0 × 10−2 kg⋅m2
d. 7.6 × 10−2 kg⋅m2

A baseball pitcher loosens up his pitching arm. He tosses a 0.15-kg ball
using only the
rotation of his forearm, 0.32 m in length, to accelerate the ball. If the ball
starts at rest and is
released with a speed of 12 m/s in a time of 0.40 s, what torque is applied to
the ball while
being held by the pitcher’s hand to produce the angular acceleration?
a. 1.1 N⋅m
b. 11 N⋅m
c. 7.2 N⋅m
d. 1.4 N⋅m – correct

A bucket of water with total mass 23 kg is attached to a rope, which in turn
is wound around
a 0.050-m radius cylinder at the top of a well. A crank with a turning radius
of 0.25 m is
attached to the end of the cylinder and the moment of inertia of cylinder and
crank is 0.12
kg⋅m2
. If the bucket is raised to the top of the well and released, what is the
acceleration of
the bucket as it falls toward the bottom of the well? (Assume rope’s mass is
negligible, that
cylinder turns on frictionless bearings and that g = 9.8 m/s2
.)
a. 3.2 m/s2 – correct
b. 6.3 m/s2
c. 7.4 m/s2
d. 9.8 m/s2

A bucket of water with total mass 23
kg is attached to a rope, which in turn is wound around
a 0.050-m radius cylinder at the top of a well. The bucket is raised to the top
of the well and
released. The bucket is moving with a speed of 8.0 m/s upon hitting the water
surface in the
well. What is the angular speed of the cylinder at this instant?

A majorette takes two batons and fastens them together in the middle at
right angles to make
an “x” shape. Each baton was 0.80 m long and each ball on the end is
0.20 kg. (Ignore the
mass of the rods.) What is the moment of inertia if the arrangement is spun
around an axis
formed by one of the batons?
a. 0.048 kg⋅m2
b. 0.064 kg⋅m2 – correct
c. 0.19 kg⋅m2
d. 0.32 kg⋅m2

In order to overcome a surface tension of a fluid, a force of 1.32 × 10-2 N is required to lift a
wire ring of circumference 12.0 cm. What is the surface tension of the fluid?
a. 0.055 N/m – correct
b. 0.11 N/m
c. 0.035 N/m
d. 0.018 N/m

A majorette takes two batons and fastens them together in the middle at
right angles to make
an “x” shape. Each baton was 0.80 m long and each ball on the end is
0.20 kg. (Ignore the
mass of the rods.) What is the moment of inertia if the arrangement is spun
around an axis
through the center perpendicular to both rods?
a. 0.064 kg⋅m2
b. 0.096 kg⋅m2
c. 0.13 kg⋅m2 – correct
d. 0.32 kg⋅m

A solid cylinder (I = MR2
/2) has a string wrapped around it many times. When I release the
cylinder, holding on to the string, the cylinder falls and spins as the string
unwinds. What is
the downward acceleration of the cylinder as it falls?
a. 0
b. 4.9 m/s2
c. 6.5 m/s2 – correct
d. 9.8 m/s2

A 40-kg boy is standing on the edge of a stationary 30-kg platform that is
free to rotate. The
boy tries to walk around the platform in a counterclockwise direction. As he
does:
a. the platform doesn’t rotate.
b. the platform rotates in a clockwise direction just fast enough so that the
boy remains
stationary relative to the ground.
c. the platform rotates in a clockwise of
direction while the boy goes around in a
counterclockwise direction relative to the ground.
– correct
d. both go around with equal angular velocities but in opposite directions.

A rod of length L is hinged at one end. The moment of inertia as the rod
rotates around that
hinge is ML2
/3. Suppose a 2.00-m rod with a mass of 3.00 kg is hinged at one end and is
held
in a horizontal position. The rod is released as the free end is allowed to
fall. What is the
angular acceleration as it is released?

Two hoops or rings (I = MR2
) are centered, lying on a turntable. The smaller ring has radius =
0.050 m; the larger has radius = 0.10 m. Both have a mass of 3.0 kg. What is
the total
moment of inertia as the turntable spins? Ignore the mass of the turntable.
a. 0.030 kg⋅m2
b. 0.007 5 kg⋅m2
c. 0.038 kg⋅m2 – correct
d. 0.075 kg⋅m2

In order to overcome a surface tension of a fluid, a force of 1.32 × 10-2 N is required to lift a
wire ring of circumference 12.0 cm. What is the surface tension of the fluid?
a. 0.055 N/m – correct
b. 0.11 N/m
c. 0.035 N/m
d. 0.018 N/m

An automobile accelerates from zero to 30 m/s in 6.0 s. The wheels have a
diameter of 0.40
m. What is the average angular acceleration of each wheel?

An object consists of a rod (of
length 3.0 m and negligible moment of inertia) to which four
small 2.0-kg masses are attached, one at each end and one at each point on the
rod 1.0 m from
each end. (The masses are one meter apart.) The moment of inertia of this
axis perpendicular to the rod and through one of the inner masses:
a. is 72 kg⋅m2
.
b. is 12 kg⋅m2 – correct
.
c. is 4 kg⋅m2
.
d. cannot be uniquely determined until it is stated which inner mass the axis
goes through.

A ventilation fan with a moment of inertia of 0.034 kg⋅m2
has a net torque of 0.11 N⋅m
applied to it. If it starts from rest, what kinetic energy will it have 8.0 s
later?
a. 31 J
b. 17 J
c. 11 J – correct
d. 6.6 J

45. The total kinetic energy of a baseball thrown with a spinning motion is
a function of:
a. its linear speed but not rotational speed.
b. its rotational speed but not linear speed.
c. both linear and rotational speeds. – correct
d. neither linear nor rotational speed.

A bowling ball has a mass of 7.0 kg, a moment of inertia of 2.8 × 10−2
kg⋅m2
0.10 m. If it rolls down the lane without slipping at a linear speed of 4.0
m/s, what is its total
kinetic energy?
a. 45 J
b. 32 J
c. 11 J
d. 78 J – correct

In order to overcome a surface tension of a fluid, a force of 1.32 × 10-2 N is required to lift a
wire ring of circumference 12.0 cm. What is the surface tension of the fluid?
a. 0.055 N/m – correct
b. 0.11 N/m
c. 0.035 N/m
d. 0.018 N/m

A bucket of water with total mass 23
kg is attached to a rope, which in turn is wound around
a 0.050-m radius cylinder, with crank, at the top of a well. The moment of
inertia of the
cylinder and crank is 0.12 kg⋅m2
. The bucket is raised to the top of the well and released to
fall back into the well. What is the kinetic energy of the cylinder and crank
at the instant the
bucket is moving with a speed of 8.0 m/s?
a. 2.1 × 103 J
b. 1.5 × 103 J – correct
c. 0.70 × 103 J
d. 0.40 × 103 J

A solid sphere of mass 4.0 kg and radius 0.12 m is at rest at the top of a
ramp inclined 15°. It
rolls to the bottom without slipping. The upper end of the ramp is 1.2 m higher
than the lower
end. Find the sphere’s total kinetic energy when it reaches the bottom.
a. 70 J
b. 47 J – correct
c. 18 J
d. 8.8 J

A solid sphere of mass 4.0 kg and radius 0.12 m starts from rest at the top
of a ramp inclined
15°, and rolls to the bottom. The upper end of the ramp is 1.2 m higher than
the lower end.
What is the linear speed of the sphere when it reaches the bottom of the ramp?
(Note: I = 0.4MR2 for a solid sphere and g = 9.8 m/s2)
a. 4.7 m/s
b. 4.1 m/s – correct
c. 3.4 m/s
d. 2.4 m/s

. A solid cylinder of mass 3.0 kg and radius 0.2 m starts from rest at the
top of a ramp, inclined
15°, and rolls to the bottom without slipping. (For a cylinder I = 0.5MR2
) The upper end of
the ramp is 1.2 m higher than the lower end. Find the linear speed of the
cylinder when it
reaches the bottom of the ramp. (g = 9.8 m/s2)
a. 4.7 m/s
b. 4.3 m/s
c. 4.0 m/s – correct
d. 2.4 m/s

A gyroscope has a moment of inertia of 0.14 kg⋅m2
and an initial angular speed of 15 rad/s.
Friction in the bearings causes its speed to reduce to zero in 30 s. What is
the value of the
average frictional torque?
a. 3.3 × 10−2 N⋅m
b. 8.1 × 10−2 N⋅m
c. 14 × 10−2 N⋅m
d. 7.0 × 10−2 N⋅m – correct

A gyroscope has a moment of inertia of 0.140 kg⋅m2 and has
an initial angular speed of 15.0
rad/s. If a lubricant is applied to the bearings of the gyroscope so that
frictional torque is
reduced to 2.00 × 10−2
N⋅m,
then in what time interval will the gyroscope coast from 15.0
a. 150 s
b. 105 s – correct
c. 90.0 s
d. 180 s

In order to overcome a surface tension of a fluid, a force of 1.32 × 10-2 N is required to lift a
wire ring of circumference 12.0 cm. What is the surface tension of the fluid?
a. 0.055 N/m – correct
b. 0.11 N/m
c. 0.035 N/m
d. 0.018 N/m

.A cylinder with its mass concentrated toward the center has a moment of
inertia of 0.1 MR2
.
If this cylinder is rolling without slipping along a level surface with a
linear speed v, what is
the ratio of its rotational kinetic energy to its linear kinetic energy?
a. 1/l0 – correct
b. 1/5
c. 1/2
d. 1/1

A solid sphere with mass, M, and radius, R, rolls along a level surface
without slipping with a
linear speed, v. What is the ratio of rotational to linear kinetic energy? (For
a solid sphere, I = 0.4 MR2).
a. 1/4
b. 1/2
c. 1/1
d. 2/5 – correct

A rotating flywheel can be used as a method to store energy. If it is
required that such a
device be able to store up to a maximum of 1.00 × 106
J when rotating at 400 rad/s, what
moment of inertia is required?
a. 50 kg⋅m2
b. 25 kg⋅m2
c. 12.5 kg⋅m2 – correct
d. 6.3 kg⋅m2

A rotating flywheel can be used as a
method to store energy. If it has 1.0 × 106
J of kinetic
energy when rotating at 400 rad/s, and if a frictional torque of 4.0 N⋅m
acts on the system, in
what interval of time would the flywheel come to rest?
a. 3.5 min
b. 7.0 min
c. 14 min
d. 21 min – correct

An initially installed flywheel can store 106
J of kinetic energy when rotating at 300 rad/s. It
is replaced by another flywheel of the same size but made of a lighter and
stronger material.
If its mass is half that of the original and it is now capable of achieving a
rotational speed of
600 rad/s, what maximum energy can be stored?
a. 40 × 105 J
b. 20 × 105 J – correct
c. 10 × 105 J
d. 5.0 × 105 J

A meter stick is hinged at its lower
end and allowed to fall from a vertical position. If its
moment of inertia is ML2
/3, with what angular speed does it hit the table?

A bus is designed to draw its power
from a rotating flywheel that is brought up to its
maximum speed (3 000 rpm) by an electric motor. The flywheel is a solid
cylinder of mass
500 kg and radius 0.500 m (Icylinder = MR2
/2). If the bus requires an average power of 10.0
kW, how long will the flywheel rotate?
a. 154 s
b. 308 s – correct
c. 463 s
d. 617 s

An object of radius R and moment of inertia I rolls down an incline of
height H after starting
from rest. Its total kinetic energy at the bottom of the incline:
a. is gR/I.
b. is I/gH.
c. is 0.5 Ig/H.
d. cannot be found from the given information alone. – correct

A uniform solid sphere rolls down an
incline of height 3 m after starting from rest. In order
to calculate its speed at the bottom of the incline, one needs to know:
a. the mass of the sphere.
b. the radius of the sphere.
c. the mass and the radius of the sphere.
d. no more than is given in the problem. – correct

In order to overcome a surface tension of a fluid, a force of 1.32 × 10-2 N is required to lift a
wire ring of circumference 12.0 cm. What is the surface tension of the fluid?
a. 0.055 N/m – correct
b. 0.11 N/m
c. 0.035 N/m
d. 0.018 N/m

Consider the use of the terms “rotation” and “revolution”. In physics:
a. the words are used interchangeably.
b. the words are used interchangeably but “rotation” is the preferred word.
c. the words have different meaning. – correct
d. “rotation” is the correct word and “revolution” should not be used.

A solid disk of radius R rolls down
an incline in time T. The center of the disk is removed up
to a radius of R/2. The remaining portion of the disk with its center gone is
again rolled
down the same incline. The time it takes is:
a. T.
b. more than T. – correct
c. less than T.
d. requires more information than given in the problem to figure out.

The quantity “angular
momentum” (in terms of the fundamental quantities of mass, length,
and time) is equivalent to:
a. MLT−2
.
b. ML2 T−1 – correct
.
c. ML2
T−3
.
d. ML3
T.

A ventilation fan with a moment of inertia of 0.034 kg⋅m2
has a net torque of 0.11 N⋅m
applied to it. If it starts from rest, what angular momentum will it have 8.0 s
later?
a. 0.88 kg⋅m2/s – correct
b. 0.97 kg⋅m2/s
c. 2.0 kg⋅m2/s
d. 3.25 kg⋅m2/s

A figure skater with arms initially
extended starts spinning on the ice at 3 rad/s. She then
pulls her arms in close to her body. Which of the following results?
a. a smaller rotational rate
b. a greater rotational rate – correct
c. a greater angular momentum
d. a smaller angular momentum

An ice skater spins at 2.5 rev/s when
his arms are extended. He draws his arms in and spins at
6.0 rev/s. By what factor does his moment of inertia change in the process?
a. 2.4
b. 1.0
c. 0.42 – correct
d. 0.12

A figure skater on ice with arms extended, spins at a rate of 2.5 rev/s.
After he draws his arms
in, he spins at 6.0 rev/s. By what factor does the skater’s kinetic energy
change when he
draws his arms in?
a. 2.4 – correct
b. 1.0
c. 0.42
d. 0.12

70. A turntable has a moment of inertia of 3.00 × 10−2
kg⋅m2
and spins freely on a frictionless
bearing at 25.0 rev/min. A 0.300-kg ball of putty is dropped vertically onto
the turntable and
sticks at a point 0.100 m from the center. What is the new rate of rotation of
the system?
a. 40.8 rev/min
b. 22.7 rev/min – correct
c. 33.3 rev/min
d. 27.2 rev/min

A turntable has a moment of inertia of 3.00 × 10−2
kg⋅m2
and spins freely on a frictionless
bearing at 25.0 rev/min. A 0.300-kg ball of putty is dropped vertically on the
turntable and
sticks at a point 0.100 m from the center. By what factor does the angular momentum
of the
system change after the putty is dropped onto the turntable?
a. 1.22
b. 1.00 (no change) – correct
c. 0.820
d. 1.50

A turntable has a moment of inertia
of 3.0 × 10−2
kg⋅m2
and spins freely on a frictionless
bearing at 25 rev/min. A 0.30-kg ball of putty is dropped vertically on the
turntable and sticks
at a point 0.10 m from the center. By what factor does the kinetic energy of
the system
change after the putty is dropped onto the turntable?
a. 0.91 – correct
b. 1.0
c. 0.82
d. 1.5

A cylinder (I = MR2/2) is rolling along the ground at 7.0 m/s. It comes to a hill and starts
going up. Assuming no losses to friction, how high does it get before it stops?
a. 1.2 m
b. 3.7 m – correct
c. 4.2 m
d. 5.9 m

Homepage