Rotational Exam Physics 121 Davis BYU Winter 2017
Two are correct (enter answers separated by a comma followed by a space): A disc is rotating about its center of mass. Point A is 0.06 m from the axis of rotation. Point B is 0.12 m from the axis of rotation. What quantities are the same for both points? A. The angular displacement. B. The linear displacement. C. The angular velocity. D. The tangential velocity.
A, C
Two are correct (enter answers separated by a comma followed by a space): A meteor of mass, M moves with a constant speed, v in a circular orbit of radius R. Which of the following statements are true? A. The tangential acceleration is zero. B. The tangential acceleration is a constant, non zero value. C. Its angular momentum is not constant. D. The magnitude of the centripetal acceleration is constant.
A, D
A ball is attached to a string and rotates in a circle. If it takes 1.00 s to complete one revolution, what is the angular velocity of the ball? A. 3.14 rad/s B. 6.28 rad/s C. 9.42 rad/s D. 12.6 rad/s
B
A bicycle wheel of radius 40.0 cm and angular velocity of 10.0 rad/s starts accelerating at 80.0 rad/s^2 . What is the tangential acceleration of the wheel at this time point? A. 4 m/s^2 B. 32 m/s^2 C. 40 m/s^2 D. 320 m/s^2
B
A bucket on the circumference of a water wheel travels an arc length of 18 m. If the radius of the wheel is 4.1 m, what is the angular displacement of the bucket? a. 1.0 rad c. 3.7 rad b. 4.4 rad d. 2.3 rad
B
A car's tire of radius 0.50 m has an angular velocity of ω = 3t^2 - 5t + 20. Find the angular velocity of the tire at t = 2.0 s. A. 14 rad/s B. 22 rad/s C. 24 rad/s D. 28 rad/s
B
A car's tire of radius 0.50 m has an angular velocity of ω = 3t^2 - 5t + 20. Find the linear velocity of the tire at t = 2.0 s. A. 7 m/s B. 11 rad/s C. 12 rad/s D. 14 rad/s
B
A cylinder with a diameter of 0.150 m rotates in a lathe at a constant angular speed of 35.6 rad/s. What is the tangential speed of the surface of the cylinder? a. 2.67 m/s c. 2.37 × 10^2 m/s b. 5.34 m/s d. 4.75 × 10^2 m/s
B
A rod rotates about a pivot at its center at 2 rad/s. Its angular velocity increases uniformly to 14 rad/s in 3 s. Find the rod's angular acceleration over this time period. A. 2 rad/s^2 B. 4 rad/s^2 C. 6 rad/s^2 D. 8 rad/s^2
B
A string is wound tightly around a fixed pulley having a radius of 5.0 cm. As the string is pulled, the pulley rotates without any slipping of the string. What is the angular speed of the pulley when the string is moving at 5.0 m/s? A) 25 rad/s B) 100 rad/s C) 20 rad/s D) 10 rad/s E) 50 rad/s
B
A tire is rolling with an initial angular velocity of 10.0 rad/s. It slows down with an angular acceleration of -5.0 rad/s^2 and comes to rest. What is the net angular displacement of the wheel? A. 5 rad B. 10 rad C. 25 rad D. 30 rad
B
A uniform meterstick of mass .20 kg is pivoted at the 40 cm mark. Where should one hang a mass of 0.5 kg to balance the stick? A)16 cm B)36 cm C)44 cm D)46 cm
B
According to Newton's second law, the angular acceleration experienced by an object is directly proportional to which of the following? a. the object's moment of inertia c. the size of the object b. the net applied torque d. the mass of the object
B
Is there an outward force in circular motion? A) Yes B) No
B
A figure skater with arms drawn in spins on the ice at a rate of 5.0 rad/s and has a moment of inertia of 1.875 kg•m^2 . What is the angular momentum of the skater? a. 2.5 kg•m^2/s b. 3.8 kg•m^2/s c. 9.4 kg•m^2/s d. 12 kg•m^2/s
C
A potter's wheel moves from rest to an angular speed of 0.54 rad/s in 30.0 s. What is the angular acceleration of the wheel? a. 16 rad/s^2 c. 0.018 rad/s^2 b. 1.3 rad/s^2 d. 0.042 rad/s^2
C
An object starts from rest and accelerates at a constant rate in a circular path. After a certain time t, the object reaches the angular velocity ω. How many revolutions did it make during time t? A. 4𝜋𝜔 B. 4𝜔/𝜋𝑡 C. 𝜔𝑡/4𝜋 D. 4𝜔𝑡
C
An object starts from rest and accelerates at a constant rate α in a circular path with a radius R. The radius describes an angle θ after time t. Which of the following represents the angular velocity as a function of θ? A. 2𝛼𝜃 B. 2𝜃/𝛼 C. √2𝛼𝜃 D. √2𝜃/𝛼
C
Consider a rigid body that is rotating. Which of the following is an accurate statement? A) Its center of rotation must be moving with a constant velocity. B) Its center of rotation must be at rest, i.e., not moving. C) All points on the body are moving with the same angular velocity. D) All points on the body are moving with the same linear velocity. E) Its center of rotation is its center of gravity.
C
Which of these is the correct unit for torque? A)N / m B)N * m^2 C)m * N D)m/N
C
A ball rolls downhill with an angular speed of 2.5 rad/s and has a constant angular acceleration of 2.0 rad/s^2 . If the ball takes 11.5 s to reach the bottom of the hill, what is the final angular speed of the ball? a. 13 rad c. 33 rad/s b. 31 rad/s d. 25.5 rad/s
D
The operator of a small carousel at a fair applies a force of 60 N to the free end a beam which is attached to the carousel. The angle between the beam and the force applied is 30 degrees. What is the amount of torque applied by the operator to the carousel if the length of the beam is 2 m? A) 120 N m B) 30 N m C) 15 N m D) 60 N m
D
Torque is the rotational analog of which of the following quantities? A. kinetic energy B. linear momentum C. acceleration D. force
D
What is the approximate angular speed of a wheel rotating at the rate of 5.0 rev/s? a. 3.2 rad/s c. 16 rad/s b. 1.6 rad/s d. 31 rad/s
D
True or False? Newton's First Law does not apply to rotating objects.
False
Which of the following quantities measures the ability of a force to rotate or accelerate an object around an axis? a. axis of rotation c. moment arm b. lever arm d. torque
d
A boy and a girl are balanced on a massless seesaw. The boy has a mass of 60 kg and the girl's mass is 50 kg. If the boy sits 1.5 m from the pivot point on one side of the seesaw, where must the girl sit on the other side for equilibrium? A) 1.8 m B) 1.3 m C) 2.5 m D) 3.0 m E) 1.2 m
A
Consider a uniform hoop of radius R and mass M rolling without slipping. Which is larger, its translational kinetic energy or its rotational kinetic energy? A) Both are equal. B) Rotational kinetic energy is larger. C) Translational kinetic energy is larger. D) You need to know the speed of the hoop to tell.
A
The moment of inertia of a cylinder is 0.016 kg•m^2. If the angular speed is 15.7 rad/s, what is the angular momentum of the cylinder? a. 0.25 kg•m^2/s b. 12.1 kg•m^2/s c. 19.2 kg•m^2/s d. 28.6 kg•m^2/s
A
The operator of a small carousel at a fair applies a force of 100 N to the free end of a beam which is rotating about the beam's axis of rotation. The angle between the beam and the force applied is 90 degrees. What is the amount of torque applied by the person if the length of the beam is 1 m? A) 100 N m B) 50 N m C) 150 N m D) 75 N m
A
Two equal-magnitude forces are applied to a door at the doorknob. The first force is applied perpendicular to the door, and the second force is applied at 30° to the plane of the door. Which force exerts the greater torque about the door hinge? A) the first force (applied perpendicular to the door) B) the second force (applied at an angle) C) Both forces exert zero torque. D) Both forces exert equal non-zero torques.
A
Two forces produce equal torques on a door about the door hinge. The first force is applied at the midpoint of the door; the second force is applied at the doorknob. Both forces are applied perpendicular to the door. Which force has a greater magnitude? A) the first force (at the midpoint) B) the second force (at the doorknob) C) The two forces are equal.
A
Two uniform disks have the same mass but different radii: disk 1 has a radius R and disk 2 has a radius 2R. What is the ratio of the moment of inertia of the first disk to the second disk? A 1:4 B. 1:2 C. 2:1 D. 4:1
A
Which of the following represents Newton's second law for rotating objects? a. net torque = moment of inertia × angular acceleration b. net torque = moment of inertia ÷ angular acceleration c. force = mass × acceleration d. force = mass ÷ acceleration
A
Which of these options listed below correctly defines a torque? A) It is the product of force and the lever arm, where the lever arm is the perpendicular distance from the axis of rotation to the line along which the force is acting. B) It is the product of mass and the lever arm, where the lever arm is the parallel distance from the axis of rotation to the line along which the weight is acting. C) It is the product of mass and the lever arm, where the lever arm is the perpendicular distance from the axis of rotation to the line along which the weight is acting. D) It is the product of force and the lever arm, where the lever arm is the parallel distance from the axis of rotation to the line along which the force is acting.
A
How would an angle in radians be converted to an angle in degrees? a. The angle in radians would be multiplied by 180°/π. b. The angle in radians would be multiplied by 360°/π. c. The angle in radians would be multiplied by 180°/2π. d. The angle in radians would be multiplied by 2π/360°.
a
Which of the following statements is correct? a. The farther the force is from the axis of rotation, the more torque is produced. b. The closer the force is to the axis of rotation, the more torque is produced. c. The closer the force is to the axis of rotation, the easier it is to rotate the object. d. The farther the force is from the axis of rotation, the less torque is produced.
a
6. A carousel with radius r is initially at rest. The carousel begins to accelerate to constantly until it reaches an angular velocity of ω, which takes two revolutions. What is the angular acceleration of the carousel during this time? A.) 𝜔^2/8𝜋 B.) 𝜔^2/4𝜋 C.) 𝜔/4𝜋 D.) 𝜔/8𝜋 E.) 𝜔^2/16𝜋
A
A bicycle wheel of radius r rolls with a constant angular velocity on a horizontal surface without slipping. Which of the following is the right formula for the velocity of the center of mass? A. 𝑣 = 𝑟𝜔 B. 𝑣 = 𝑟/𝜔 C. 𝑣 = 𝜔/𝑟 D. 𝑣 = 𝜔^2𝑟
A
A child sits on a carousel at a distance of 3.5 m from the center and rotates through an arc length of 6.5 m. What is the angular displacement of the child? a. 1.9 rad c. 3.0 rad b. 0.93 rad d. 5.0 rad
A
In which of these cases do we need to apply a torque on an object? A) to rotate an object B) to slow the rotation of an object C) to slide an object D) to stop the sliding of an object E) c and d F) a and b
F
A contestant in a game show spins a stationary wheel with a radius of 0.50 m so that it has a constant angular acceleration of 0.40 rad/s^2 . What is the tangential acceleration of a point on the edge of the wheel? a. 0.20 m/s^2 c. 1.3 m/s^2 b. 0.60 m/s^2 d. 0.73 m/s^2
A
A merry-go-round spins freely when Diego moves quickly to the center along a radius of the merry-go-round. As he does this, it is true to say that A) the moment of inertia of the system decreases and the angular speed increases. B) the moment of inertia of the system decreases and the angular speed remains the same. C) the moment of inertia of the system decreases and the angular speed decreases. D) the moment of inertia of the system increases and the angular speed increases. E) the moment of inertia of the system increases and the angular speed decreases
A
A record player is turned on and reaches an angular velocity of 4.7 rad/s in 1.37 s. What is the average angular acceleration of the record? a. 3.4 rad/s^2 c. 6.4 rad/s^2 b. 4.3 rad/s^2 d. 0.29 rad/s^2
A
A solid sphere and a solid cylinder, both uniform and of the same mass and radius, roll without slipping at the same forward speed. It is correct to say that the total kinetic energy of the solid sphere is A) less than the total kinetic energy of the cylinder. B) equal to the total kinetic energy of the cylinder. C) more than the total kinetic energy of the cylinder.
A
A toy car moves around a circular track with a radius of 10 m. When the car's velocity is instantaneously directed south, its acceleration is directed west at 10 m/s^2 . When viewed from above, the car moves: A. clockwise at 1 rad/s B. clockwise at 10 rad/s C. counterclockwise at 1 rad/s D. counterclockwise at 10 rad/s
A
A wheel with rotational inertia, I is placed on an axle and is free to rotate without friction. The angular speed, ω of the wheel is increased from zero to ωfinal in a time interval, t. What is the average net torque on the wheel during this time interval? A. (𝐼 x 𝜔𝑓inal)/(𝑡) B. (𝜔𝑓inal)/(𝑡^2) C. (𝐼 x 𝜔𝑓inal^2)/(t) D. (𝐼 x 𝜔𝑓inal)/(𝑡^2)
A
An ice skater performs a fast spin by pulling her outstretched arms down and close to her body. What happens to her kinetic energy? A. increases B. decreases C. stays the same D. depends on her initial rotational velocity
A
An object has a final angular velocity of 25 rad/s and sweeps through 80.0 rads with an angular acceleration of 2.5 rad/s^2. What was its initial angular velocity? A. 15 rad/s B. 25 rad/s C. 32 rad/s D. 48 rad/s
A
Two are correct (enter answers separated by a comma followed by a space): Which of the following situations will increase the moment of inertia of a solid cylinder (I = ½ MR2 ) by the same amount? A. Constant mass, double radius. B. Quadruple mass, constant radius. C. Double mass, constant radius. D. Constant mass, quadruple radius.
A, B
A disc rotates through 10 radians in 4 seconds. The disc experienced uniform acceleration. If the disc starts from rest, what is the angular velocity after four seconds? A.) 2.5 rad/s B.) 5 rad/s C.) 40 rad/s D.) 3 rad/s E.) 42 rad/s
B
A flywheel with a radius of 0.30 m starts from rest and accelerates with a constant angular acceleration of 0.50 rad/s^2 . What is the tangential acceleration of the flywheel? a. 0.63 m/s^2 b. 0.15 m/s^2 c. 0.65 m/s^2 d. 1.30 m/s^2
B
A force of 45 N is applied to a door at an angle of 300 to the plane of the door and at a distance of 3.5 m from the axis of rotation. Which expression represents the torque applied about the door's axis of rotation? A) 1300 N m B) 1250 N m C) 1000 N m D) 1500 N m
B
A meterstick of negligible mass is placed on a fulcrum at the 0.6m mark, with a 2.0kg mass hung at the 0 m mark and a 1.0 kg mass hung at the 1.0m mark. The meterstick is released from rest in a horizontal position immediately after release, the magnitude of the net torque on the meterstick about the fulcrum is most nearly: A)2.0 Nm B)8.0 Nm C)10 Nm D)16 Nm
B
A record on a turntable is spinning and coming to rest. At t = 0 s, the angular velocity of the record is 20.0 rad/s with a constant acceleration of - 5.0 rad/s^2 What is the record's angular displacement at t = 2.0 s? A. 15 rad B. 30 rad C. 40 rad D. 50 rad
B
A record on a turntable is spinning and coming to rest. At t = 0 s, the angular velocity of the record is 20.0 rad/s with a constant acceleration of - 5.0 rad/s^2. How long does it take for the record to come to rest? A. 2 s B. 4 s C. 8 s D. 12 s
B
An object has an initial angular velocity of 5.00 rad/s and undergoes a constant angular acceleration of -0.100 rad/s^2. What is the angular displacement that it moves through in 3.00 s? A. 12.3 rad B. 14.6 rad C. 16.3 rad D. 19.3 rad
B
How would you convert an angle in degrees to an angle in radians? a. multiply the angle measured in degrees by 2π/180° b. multiply the angle measured in degrees by 2π/360° c. multiply the angle measured in degrees by π/360° d. multiply the angle measured in degrees by 2πr°
B
In translational motion, mass is a measure of an object's acceleration in response to a force. What is the rotational analog of mass? A. torque B. moment of inertia C. angular acceleration D. angular momentum
B
Suppose a doorknob is placed at the center of a door. Compared with a door whose knob is located at the edge, what amount of force must be applied to this door to produce the torque exerted on the other door? a. one-half as much c. one-fourth as much b. two times as much d. four times as much
B
Suppose a solid uniform sphere of mass M and radius R rolls without slipping down an inclined plane starting from rest. The angular velocity of the sphere at the bottom of the incline depends on A) the mass of the sphere. B) the radius of the sphere. C) both the mass and the radius of the sphere. D) neither the mass nor the radius of the sphere.
B
The magnitude of torque acting on a point is given by r F sin θ. Which of these is the correct explanation for angle θ? A)It is the angle between the force and the axis of rotation. B) It is the angle between the force and the radial distance between the force and axis of rotation. C) It is the angle between the rod and the axis of rotation. D) It is the angle between the force and the normal to the axis of rotation.
B
The moment of inertia of a solid cylinder about its axis is given by 0.5MR^2. If this cylinder rolls without slipping, the ratio of its rotational kinetic energy to its translational kinetic energy is A) 3:1 B) 1:2 C) 1:3 D) 2:1 E) 1:1
B
The units for moment of inertia are _______. A.) N B.) Kg * m^2 C.) Kg^2 * m D.) Kg/m E.) Kg *N^2
B
Two uniform disks have the same radius but different masses: disk 1 has a mass M, disk 2 has a mass 2M. What is the ratio of the moment of inertia of the first disk to the second disk? A. 1:4 B. 1:2 C. 2:1 D. 4:1
B
What does the moment of inertia describe? A.) The average position of mass in an extended object. B.) How the mass of an object is distributed about a rotational axis. C.) How a force can rotate an object. D.) The tendency of an object to move in a straight line. E.) The linear acceleration of an object.
B
What represents the relation between the force, the lever arm and the torque acting on an object ? A) torque = (force) ( lever arm)^2 B) torque = force X lever arm C) torque = (force) / ( lever arm) D) torque = (force) / ( lever arm)^2
B
When is the angular momentum of a system constant? A) Only when the linear momentum and the energy are constant. B) Only when no net external torque acts on the system. C) Only when its total kinetic energy is constant. D) Only when no net external force acts on the system. E) Only when the moment of inertia is constant.
B
Which of the following statements is correct? a. With a net positive torque, the angular acceleration of an object is clockwise. b. With a net positive torque, the angular acceleration of an object is counterclockwise. c. With a net negative torque, the angular acceleration of an object is counterclockwise. d. The net force of an object is not related to the translational acceleration given to the object.
B
Which of these define a torque? A) A force that causes a moving object to stop its translational movement. B) A force that causes an object to rotate. C) A force that allows an object to move with constant translational velocity. D) A force that causes an object to move in translational motion.
B
Why do we need to know the length of the lever arm? A) to calculate the length of the rod on which the force is applied B) to calculate the torque applied about the axis of rotation C) to calculate the force applied about the axis of rotation D) to calculate the amount of magnification in the applied force
B
Two are correct (enter answers separated by a comma followed by a space): Leonardo da Vinci conceived of a flywheel with a variable moment of inertia. It consisted of a vertical axle, with four rods attached to the axle in a horizontal manner, equally spaced around the axle. At the end of each rod, a small chain hung vertically with a sphere attached to the bottom of each chain. If an external torque was applied to the axle, it would rotate and the spheres would move outward and upward from the axle. Which of the following statements are true? A. The angular momentum of the flywheel is conserved. B. The angular momentum of the flywheel is not conserved. C. The moment of inertia of the flywheel increases. D. The moment of inertia of the flywheel decreases.
B, C
Two are correct (enter answers separated by a comma followed by a space): Two students of different masses are about to get on a see-saw. If they want to place the see-saw in equilibrium, what factors must they consider? A. The mass of the see-saw plank that they sit on. B. The mass of each student. C. The distance each student sits away from the fulcrum of the see-saw. D. The length of the see-saw plank.
B, C
Two are correct (enter answers separated by a comma followed by a space): A solid cylinder of radius, R rolls down an incline. Which of the following objects, if set in motion at the same time on an identical incline, will get to the bottom of the incline before this hoop? A. Cylindrical shell of radius R. B. Solid sphere of radius R. C. Solid sphere of radius 2R. D. Solid cylinder of radius R/2.
B, D
A baseball player swings his bat with his arms fully extended. If his arms are pulled in closer to his body, which of the following choices correctly describes the impact of his motion on his swing's angular momentum and kinetic energy? Angular Momentum, Kinetic Energy A. increases, increases B. increases, remains constant C. remains constant, increases D. remains constant, remains constant
C
A bicycle wheel rotates with a constant angular acceleration of 3.0 rad/s2 . If the initial angular speed of the wheel is 1.5 rad/s, what is the angular displacement of the wheel after 4.0 s? a. 6.0 rad c. 30 rad b. 24 rad d. 36 rad
C
A child with a weight of 4.50 × 10^2 N sits on a seesaw 0.60 m from the axis of rotation. How far from the axis of rotation on the other side should a child with a weight of 6.00 × 10^2 N sit so the seesaw will remain balanced? a. 0.30 m c. 0.45 m b. 0.40 m d. 0.50 m
C
A disk, a hoop, and a solid sphere are released at the same time at the top of an inclined plane. They are all uniform and roll without slipping. In what order do they reach the bottom? A) hoop, sphere, disk B) hoop, disk, sphere C) sphere, disk, hoop D) disk, hoop, sphere E) sphere, hoop, disk
C
A solid disk with a radius R rotates at a constant rate ω. Which of the following represents the period of rotations? A. 2𝜋𝜔 B. 𝜋/2𝜔 C. 2𝜋/𝜔 D. 2𝜔
C
An ice skater is spinning fast with her arms tight against her body. When she extends her arms, which of the following statements is NOT true? A.) She increases her moment of inertia. B.) She decreases her angular velocity. C.) Her moment of inertia remains constant. D.) Her total angular momentum will remain constant. E.) She will spin slower.
C
An ice skater performs a fast spin by pulling her outstretched arms down and close to her body. What happens to her angular momentum with respect to the axis of rotation? A. increases B. decreases C. stays the same D. depends on her initial rotational velocity
C
An object has an initial angular velocity of 5.0 rad/s and undergoes an angular acceleration of 15 rad/s^2. What is the final angular velocity after 3.0 s? A. 25 rad/s B. 30 rad/s C. 50 rad/s D. 60 rad/s
C
Consider a solid uniform sphere of radius R and mass M rolling without slipping. Which form of its kinetic energy is larger, translational or rotational? A) Rotational kinetic energy is larger. B) Both are equal. C) Translational kinetic energy is larger. D) You need to know the speed of the sphere to tell.
C
Find the linear displacement of a car wheel of radius 9.0 m as it moves through an angular displacement of 3.0 rad. A. 0.33 rad B. 3.3 rad C. 27 rad D. 81 rad
C
If an object starts from rest and accelerates with a constant angular acceleration of 6.0 rad/s^2, what is the angular velocity at 3.0 s? A. 0.50 rad/s B. 2.0 rad/s C. 18 rad/s D. 54 rad/s
C
The end of the cord on a weed cutter is 0.15 m in length. If the motor rotates at the rate of 126 rad/s, what is the tangential speed of the cord? a. 628 m/s c. 19 m/s b. 25 m/s d. 63 m/s
C
Two uniform solid balls, one of radius R and mass M, the other of radius 2R and mass 8M, roll down a high incline. They start together from rest at the top of the incline. Which one will reach the bottom of the incline first? A) The large sphere arrives first. B) The small sphere arrives first. C) Both reach the bottom at the same time.
C
What is a lever arm? A) It is the distance from the axis of rotation to the free end of an object. B) It is the distance from the point where the a force is being applied to the axis of rotation. C) It is the perpendicular distance from the axis of rotation to the line along which a force is acting. D) It is the perpendicular distance from the axis of rotation to the point at which a force is acting.
C
What is the position of the center of mass for irregularly shaped objects? A) At the geometric center. B) At any point on the surface. C) Closer to the more massive end. D) Closer to the less massive end.
C
What is the symbol for angular momentum? A.) N B.) A C.) L D.) F E.) M
C
When a solid object rotates with a constant angular acceleration, which of the following is true? A. All points on the object rotate with the same centripetal acceleration. B. The net torque applied to the object must be zero. C. The net torque applied to the object must be a constant. D. All points on the object rotate with the same tangential acceleration.
C
Which of the following is the unit for angular displacement? A. meters B. seconds C. radians D. radians per second
C
Which of the following statements is correct? a. The farther the center of mass of an object is from the axis of rotation, the less difficult it is to rotate the object. b. The farther the center of mass of an object is from the axis of rotation, the smaller the object's moment of inertia is. c. The farther the center of mass of an object is from the axis of rotation, the greater the object's moment of inertia is. d. The farther the center of mass of an object is from the axis of rotation, the greater the object's moment of inertia is, but the less difficult it is to rotate the object.
C
Which of these terms define the average position of all the mass contained in a system, concentrated at a single point? A) Center of gravity B) Point of symmetry C) Center of mass D) Geometrical center
C
Two are correct (enter answers separated by a comma followed by a space): . You are choosing a screwdriver to loosen a stuck screw. Which of the following qualities of the screwdriver will allow you to deliver the most torque to the screw? A. Increased length of the screwdriver shank. B. A handle with a small diameter. C. A handle with a large diameter. D. Increased width of the blade.
C, D
Two are correct (enter answers separated by a comma followed by a space): Two children are in a playground. One of them is on a merry-go-round that is rotating in a clockwise direction, and the other one is next to the merry-go-round. Which of the following actions will result in a change in the angular momentum of the single child - merry-go-round system? A. The child on the merry-go-round moves towards the center of it. B. The child on the merry-go-round moves in a concentric circle around it. C. The other child pushes tangentially on the merry-go-round, increasing its angular velocity. D. The other child jumps on to the merry-go-round.
C, D
A bicycle wheel of radius 40.0 cm and angular velocity of 10.0 rad/s starts accelerating at 80.0 rad/s^2. What is the centripetal acceleration of the wheel at this time point? A. 12 m/s^2 B. 24 m/s^2 C. 36 m/s^2 D. 40 m/s^2
D
A bowling ball has a mass of 7.0 kg, a moment of inertia of 2.8 × 10^-2 kg•m^2, and a radius of 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 c. 11 J b. 32 J d. 78 J
D
A force of 20 N is applied on a gate at an angle of 700 at a distance of 3 m from the gate's axis of rotation. What is the torque applied on the axis of rotation if the gate swings about its hinge? A) (20 N) (3 m) sin (300) B) (20 N)^2 (3 m) sin (700) C) (20 N) (3 m)^2 sin (700) D) (20 N) (3 m) sin (700)
D
A meterstick is supported at each side by a spring scale. A heavy mass is then hung on the meterstick so that the spring scale on the left hand side reads four times the value of the spring scale on the right side. If the mass of the meterstick is negligible compared to the hanging mass, how far from the right hand side is the large mass hanging? A)25 cm B)67 cm C)75 cm D)80 cm
D
A point on the rim of a rotating wheel with a 0.37 m radius has a centripetal acceleration of 19.0 m/s^2 . What is the angular speed of the wheel? a. 0.89 m/s c. 3.2 rad/s b. 1.6 rad/s d. 7.2 rad/s
D
A record on a turntable is spinning and coming to rest. At t = 0 s, the angular velocity of the record is 20.0 rad/s with a constant acceleration of - 5.00 rad/s^2. What is the record's angular velocity at t = 0.500 s? A. 10.5 rad/s B. 15.5 rad/s C. 16.5 rad/s D. 17.5 rad/s
D
A rod rotates about a pivot at its center at 2 rad/s. Its angular velocity increases uniformly to 14 rad/s in 3 s. Find the rod's angular displacement over this time period. A. 6 rad B. 12 rad C. 18 rad D. 24 rad
D
A roller coaster loaded with passengers has a mass of 2.0 × 103 kg; the radius of curvature of the track at the lowest point of the track is 24 m. If the vehicle has a tangential speed of 18 m/s at this point, what force is exerted on the vehicle by the track? a. 2.3 × 10^4 N c. 3.0 × 10^4 N b. 4.7 × 10^4 N d. 2.7 × 10^4 N
D
An experiment is performed in a physics class where three objects, an empty can, a D battery and a marble, roll down an incline of height, H without slipping. A box slides down an adjacent frictionless incline of the same height. Which of the four objects reaches the bottom of their inclined planes first? A. empty can B. battery C. marble D. box
D
Angular momentum cannot be conserved if A) there is a net force on the system. B) the angular displacement changes. C) the moment of inertia changes. D) there is net torque on the system. E) the angular velocity changes.
D
Angular momentum is: A.) The sum of moment of inertia and angular velocity B.) The square root of angular velocity C.) The difference of angular velocity and momentum D.) The product of moment of inertia and angular velocity E.) The square root of the moment of inertia
D
The Earth moves around the Sun in an elliptical orbit. As the Earth approaches its closest point to the Sun in its orbit, the Earth's linear velocity increases. Which of the following doesn't change in the Earth-Sun system? A. orbital radius B. kinetic energy C. potential energy D. angular momentum
D
A planet of constant mass orbits the sun in an elliptical orbit. Neglecting any friction effects, what happens to the planet's rotational kinetic energy about the sun's center? A) It remains constant. B) It decreases continually. C) It increases continually. D) It decreases when the planet approaches the sun, and increases when it moves farther away. E) It increases when the planet approaches the sun, and decreases when it moves farther away
E
If a constant net torque is applied to an object, that object will A) rotate with constant linear velocity. B) having an increasing moment of inertia. C) rotate with constant angular velocity. D) having a decreasing moment of inertia. E) rotate with constant angular acceleration.
E
What condition or conditions is/are necessary for static equilibrium? A) ΣFx = 0 B) ΣFx = 0, ΣFy = 0 C) ΣFy = 0 D) Στ = 0 E) ΣFx = 0, ΣFy = 0, Στ = 0
E
Which equation should be used for the moment of inertia of a ring about an axis? A.) 1/12 M*R^2 B.) 1/2 M*R^2 C.) M*R D.) 1/2 M*R E.) M*R^2
E
A heavy bank-vault door is opened by the application of a force of 3.0 × 10^2 N directed perpendicular to the plane of the door at a distance of 0.80 m from the hinges. What is the torque? a. 120 N•m c. 300 N•m b. 240 N•m d. 360 N•m
b
The dependence of equilibrium on the absence of net torque is a. the first condition of equilibrium. c. rotational equilibrium. b. the second condition of equilibrium. d. translational equilibrium.
b