Question 1

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:

Accepted Answer

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. 
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. D

Question 2

An ice skater spins at 3.5 rev/s with his arms are extended.He draws his arms in and spins at 8.3 rev/s.By what factor does his moment of inertia change in the process?

Accepted Answer

A)  2.4 
B)  0.58 
C)  0.42 
D)  0.12 
A)  2.4 
B)  0.58 
C)  0.42 
D)  0.12 C

Question 3

A tetherball is attached to a pole with a 2.0-m rope.It is circling at 0.20 rev/s.As the rope wraps around the pole,it shortens.How long is the rope when the ball is moving at 6.0 m/s?

Accepted Answer

A)  1.8 m 
B)  0.83 m 
C)  1.2 m 
D)  1.0 m 
A)  1.8 m 
B)  0.83 m 
C)  1.2 m 
D)  1.0 m B

Question 4

A hoop 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 hoop,I = MR2. )

Accepted Answer

A)  1/4 
B)  1/2 
C)  1/1 
D)  2/5 
A)  1/4 
B)  1/2 
C)  1/1 
D)  2/5

Question 5

A non-uniform round object of mass M and radius R is found to have its total kinetic energy to be given by  
When rolling down an incline.What is this object's moment of inertia?

Accepted Answer

A) 
  
B) 
  
C) 
  
D) 
  
A) 
  
B) 
  
C) 
  
D)

Question 6

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 0.600-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?

Accepted Answer

A)  20.8 rev/min 
B)  22.7 rev/min 
C)  33.3 rev/min 
D)  27.2 rev/min 
A)  20.8 rev/min 
B)  22.7 rev/min 
C)  33.3 rev/min 
D)  27.2 rev/min

Question 7

A 40-kg boy is standing on the edge of a stationary 30-kg circular platform that is free to rotate.The boy tries to walk around the platform in a counterclockwise direction.As he does:

Accepted Answer

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 direction while the boy goes around in a counterclockwise direction relative to the ground. 
D)  both go around with equal angular velocities but in opposite directions. 
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 direction while the boy goes around in a counterclockwise direction relative to the ground. 
D)  both go around with equal angular velocities but in opposite directions.

Question 8

A solid sphere of mass 2.5 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 1.6 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. )

Accepted Answer

A)  4.7 m/s 
B)  22.4 m/s 
C)  5.6 m/s 
D)  3.3 m/s 
A)  4.7 m/s 
B)  22.4 m/s 
C)  5.6 m/s 
D)  3.3 m/s

Question 9

Consider the use of the terms "rotation" and "revolution".In physics:

Accepted Answer

A)  the words are used interchangeably. 
B)  the words are used interchangeably but "rotation" is the preferred word. 
C)  the words have different meaning. 
D)  "rotation" is the correct word,and "revolution" should not be used. 
A)  the words are used interchangeably. 
B)  the words are used interchangeably but "rotation" is the preferred word. 
C)  the words have different meaning. 
D)  "rotation" is the correct word,and "revolution" should not be used.

Question 10

A 2.0-kg mass in the xy plane is moving in the negative x direction at 3.0 m/s along the line y = 5.0 m.As the mass passes across the y axis (i.e. ,passing the point (x,y = 0,5.0 m)),what is its angular momentum with respect to the z axis?

Accepted Answer

A)  30 SI units 
B)  150 SI units 
C)  −30 SI units 
D)  −150 SI units 
A)  30 SI units 
B)  150 SI units 
C)  −30 SI units 
D)  −150 SI units

Question 11

Three disks have the same mass and the same total kinetic energy.Disk #1 has radius R,disk #2 has radius 2R,and disk #3 has radius 3R.Which one has the highest vtranslational?

Accepted Answer

A)  disk #1 
B)  disk #2 
C)  disk #3 
D)  The all have the same vtranslational. 
A)  disk #1 
B)  disk #2 
C)  disk #3 
D)  The all have the same vtranslational.

Question 12

A 6.0 kg mass in the xy plane is moving in the negative x direction at 3.0 m/s along the line y = 4.0 m.As the mass passes the point (x,y = 10 m,4.0 m),what is its angular momentum with respect to the z axis?

Accepted Answer

A)  30 SI units 
B)  72 SI units 
C)  −60 SI units 
D)  −180 SI units 
A)  30 SI units 
B)  72 SI units 
C)  −60 SI units 
D)  −180 SI units

Question 13

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 2.00 × 106 J when rotating at 400 rad/s,what moment of inertia is required?

Accepted Answer

A)  50 kg
  m2 
B)  25 kg
  m2 
C)  12.5 kg
  m2 
D)  6.3 kg
  m2 
A)  50 kg
  m2 
B)  25 kg
  m2 
C)  12.5 kg
  m2 
D)  6.3 kg
  m2

Question 14

Perihelion,the near point to the Sun for the Earth in its orbit,occurs in January.In which of the following months is the orbital angular momentum of the Earth the greatest?

Accepted Answer

A)  only in January 
B)  only in July 
C)  in both April and October,but in no other months 
D)  None of the above answers is correct. 
A)  only in January 
B)  only in July 
C)  in both April and October,but in no other months 
D)  None of the above answers is correct.

Question 15

The quantity "angular momentum" (in terms of the fundamental quantities of mass,length,and time)is equivalent to:

Accepted Answer

A)  MLT−2. 
B)  ML2T−1. 
C)  ML2T−3. 
D)  ML3T. 
A)  MLT−2. 
B)  ML2T−1. 
C)  ML2T−3. 
D)  ML3T.

Question 16

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 9.0 s later?

Accepted Answer

A)  0.88 kg·m2/s 
B)  0.99 kg·m2/s 
C)  2.0 kg·m2/s 
D)  3.25 kg·m2/s 
A)  0.88 kg·m2/s 
B)  0.99 kg·m2/s 
C)  2.0 kg·m2/s 
D)  3.25 kg·m2/s

Question 17

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 0.60-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?

Accepted Answer

A)  0.91 
B)  1.0 
C)  0.83 
D)  1.5 
A)  0.91 
B)  1.0 
C)  0.83 
D)  1.5

Question 18

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:

Accepted Answer

A)  is gR/I. 
B)  is I/gH. 
C)  is 0.5 Ig/H. 
D)  cannot be found from the given information alone. 
A)  is gR/I. 
B)  is I/gH. 
C)  is 0.5 Ig/H. 
D)  cannot be found from the given information alone.

Question 19

A hoop (I = MR2)is rolling along the ground at 10 m/s.It comes to a hill and starts going up.Assuming no losses to friction,how far does it travel vertically up the hill before it stops?

Accepted Answer

A)  10 m 
B)  3.7 m 
C)  5.1 m 
D)  7.7 m 
A)  10 m 
B)  3.7 m 
C)  5.1 m 
D)  7.7 m

Question 20

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?

Accepted Answer

A)  5.42 rad/s 
B)  2.71 rad/s 
C)  1.22 rad/s 
D)  7.67 rad/s 
A)  5.42 rad/s 
B)  2.71 rad/s 
C)  1.22 rad/s 
D)  7.67 rad/s

Exam 9: Solids and Fluids: Part A

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:

An ice skater spins at 3.5 rev/s with his arms are extended.He draws his arms in and spins at 8.3 rev/s.By what factor does his moment of inertia change in the process?

A tetherball is attached to a pole with a 2.0-m rope.It is circling at 0.20 rev/s.As the rope wraps around the pole,it shortens.How long is the rope when the ball is moving at 6.0 m/s?

A hoop 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 hoop,I = MR2. )

A non-uniform round object of mass M and radius R is found to have its total kinetic energy to be given by When rolling down an incline.What is this object's moment of inertia?

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 0.600-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-kg boy is standing on the edge of a stationary 30-kg circular platform that is free to rotate.The boy tries to walk around the platform in a counterclockwise direction.As he does:

Consider the use of the terms "rotation" and "revolution".In physics:

A 2.0-kg mass in the xy plane is moving in the negative x direction at 3.0 m/s along the line y = 5.0 m.As the mass passes across the y axis (i.e. ,passing the point (x,y = 0,5.0 m)),what is its angular momentum with respect to the z axis?

Three disks have the same mass and the same total kinetic energy.Disk #1 has radius R,disk #2 has radius 2R,and disk #3 has radius 3R.Which one has the highest vtranslational?

A 6.0 kg mass in the xy plane is moving in the negative x direction at 3.0 m/s along the line y = 4.0 m.As the mass passes the point (x,y = 10 m,4.0 m),what is its angular momentum with respect to the z axis?

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 2.00 × 106 J when rotating at 400 rad/s,what moment of inertia is required?

Perihelion,the near point to the Sun for the Earth in its orbit,occurs in January.In which of the following months is the orbital angular momentum of the Earth the greatest?

The quantity "angular momentum" (in terms of the fundamental quantities of mass,length,and time)is equivalent to:

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 9.0 s later?

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 hoop (I = MR2)is rolling along the ground at 10 m/s.It comes to a hill and starts going up.Assuming no losses to friction,how far does it travel vertically up the hill before it stops?

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?

Introduction

Introduction: Part A

Motion in One Dimension

Motion in One Dimension: Part A

Vectors and Two-Dimensional Motion

Vectors and Two-Dimensional Motion: Part A

The Laws of Motion

The Laws of Motion: Part A

Energy

Energy: Part A

Momentum and Collisions

Momentum and Collisions: Part A

Rotational Motion and the Law of Gravity

Rotational Motion and the Law of Gravity: Part A

Rotational Equilibrium and Rotational Dynamics

Rotational Equilibrium and Rotational Dynamics: Part A

Solids and Fluids

Thermal Physics

Thermal Physics: Part A

Energy in Thermal Processes Heat and Internal Energy

Energy in Thermal Processes Heat and Internal Energy: Part A

The Laws of Thermodynamics Work in Thermodynamic Processes

The Laws of Thermodynamics Work in Thermodynamic Processes: Part A

Vibrations and Waves

Vibrations and Waves: Part A

Sound

Sound: Part A

Electric Forces and Electric Fields

Electric Forces and Electric Fields: Part A

Electrical Energy and Capacitance

Electrical Energy and Capacitance: Part A

Current and Resistance Electric Current

Current and Resistance Electric Current: Part A

Direct-Current Circuits Sources of EMF

Direct-Current Circuits Sources of EMF: Part A

Magnetism Magnets

Magnetism Magnets: Part A

Induced Voltages and Inductance

Induced Voltages and Inductance: Part A

Alternating-Current Circuits and Electromagnetic Waves

Alternating-Current Circuits and Electromagnetic Waves: Part A

Reflection and Refraction of Light

Reflection and Refraction of Light: Part A

Mirrors and Lenses

Mirrors and Lenses: Part A

Wave Optics

Wave Optics: Part A

Optical Instruments

Optical Instruments: Part A

Relativity

Relativity: Part A

Quantum Physics Blackbody Radiation and Plancks Hypothesis

Quantum Physics Blackbody Radiation and Plancks Hypothesis: Part A

Atomic Physics

Atomic Physics: Part A

Nuclear Physics

Nuclear Physics: Part A

Nuclear Energy and Elementary Particles

Nuclear Energy and Elementary Particles: Part A

Particle Collisions, Mediating Photons, and Quark Structures: Exploring the Fundamentals of Physics

Filters

A hoop 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 hoop,I = MR². )

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 0.600-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?

Three disks have the same mass and the same total kinetic energy.Disk #1 has radius R,disk #2 has radius 2R,and disk #3 has radius 3R.Which one has the highest v_{translational}?

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 2.00 × 10⁶ J when rotating at 400 rad/s,what moment of inertia is required?

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 9.0 s later?

A hoop (I = MR²)is rolling along the ground at 10 m/s.It comes to a hill and starts going up.Assuming no losses to friction,how far does it travel vertically up the hill before it stops?

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?