Physics
Mechanics
Easy

Question

A solid uniform disk of mass m and radius R is pivoted about a horizontal axis through its centre and a small body of mass m is attached to the rim of the disk. If the disk is released from rest with the small body, initially at the same level as the centre, the angular velocity when the small body reaches the lowest point of the disk is

  1. square root of fraction numerator 12 g over denominator 13 r end fraction end root
  2. square root of fraction numerator 11 g over denominator 12 r end fraction end root
  3. square root of fraction numerator 12 g over denominator 11 r end fraction end root
  4. square root of fraction numerator 7 g over denominator 11 r end fraction end root

The correct answer is: square root of fraction numerator 12 g over denominator 11 r end fraction end root


    T h e space c o n s e r v a t i o n space o f space e n e r g y space y i e l d s
table attributes columnalign left columnspacing 1em rowspacing 4 pt end attributes row cell straight capital delta K. E. equals straight capital delta P. E end cell row cell 1 half I omega squared equals m g left parenthesis 2 r right parenthesis plus m g r end cell end table
table attributes columnalign left columnspacing 1em rowspacing 4 pt end attributes row cell not stretchy rightwards double arrow space of 1em 1 half m left parenthesis 2 r right parenthesis squared omega squared plus 1 half open curly brackets open parentheses fraction numerator m r squared over denominator 2 end fraction close parentheses plus m r squared close curly brackets omega squared equals 3 m g r end cell row cell not stretchy rightwards double arrow space of 1em omega equals square root of fraction numerator 12 g over denominator 11 end fraction r end root end cell end table

    Related Questions to study

    Mechanics
    Physics

    text  A composite rod comprising two rods of mass  end text straight m text  and  end text 2 straight m text  and each of length  end text l equals 1 straight m text  as shown in the  end text
text  figure. Assume  end text omega equals 10 rad divided by straight s text  and  end text straight m equals 1 kg comma text  the  end text KE text  of the rotating composite rod is  end text

    text  A composite rod comprising two rods of mass  end text straight m text  and  end text 2 straight m text  and each of length  end text l equals 1 straight m text  as shown in the  end text
text  figure. Assume  end text omega equals 10 rad divided by straight s text  and  end text straight m equals 1 kg comma text  the  end text KE text  of the rotating composite rod is  end text

    PhysicsMechanics
    Mechanics
    Physics

    text  A man stands on a rotating platform with his arms stretched holding a  end text 5 kg text  weight in each  end text
text  hand. The angular speed of the platform is 1.2revs  end text to the power of negative 1 end exponent text . The moment of inertia of the man together  end text
text  with the platform may be taken to be constant and equal to  end text 6 kgm squared text  . If the man brings his arms  end text
c l o s e space t o space h i s space c h e s t space w i t h space t h e space d i s tan c e space n space e a c h space w e i g h t space f r o m space t h e space a x i s space c h a n g i n g space f r o m space 100 space c m space t o space 20 c m. space T h e space n e w space a n g u l a r space s p e e d space o f space t h e space p l a t f o r m space i s

    text  A man stands on a rotating platform with his arms stretched holding a  end text 5 kg text  weight in each  end text
text  hand. The angular speed of the platform is 1.2revs  end text to the power of negative 1 end exponent text . The moment of inertia of the man together  end text
text  with the platform may be taken to be constant and equal to  end text 6 kgm squared text  . If the man brings his arms  end text
c l o s e space t o space h i s space c h e s t space w i t h space t h e space d i s tan c e space n space e a c h space w e i g h t space f r o m space t h e space a x i s space c h a n g i n g space f r o m space 100 space c m space t o space 20 c m. space T h e space n e w space a n g u l a r space s p e e d space o f space t h e space p l a t f o r m space i s

    PhysicsMechanics
    Mechanics
    Physics

    text  Two discs of moments of inertia  end text I subscript 1 text  and  end text I subscript 2 text  about their respective axes, rotating with angular  end text
text  frequencies,  end text omega subscript 1 text  and  end text omega subscript 2 text  respectively, are brought into contact face to face with their axes of  end text
text  rotation coincident. The angular frequency of the composite disc will be A  end text

    text  Two discs of moments of inertia  end text I subscript 1 text  and  end text I subscript 2 text  about their respective axes, rotating with angular  end text
text  frequencies,  end text omega subscript 1 text  and  end text omega subscript 2 text  respectively, are brought into contact face to face with their axes of  end text
text  rotation coincident. The angular frequency of the composite disc will be A  end text

    PhysicsMechanics
    parallel
    Mechanics
    Physics

    A space c h i l d space i s space s tan d i n g space w i t h space h i s space t w o space a r m s space o u t s t r e t c h e d space a t space t h e space c e n t r e space o f space a space t u r n t a b l e space t h a t space i s space r o t a t i n g space a b o u t space i t s space c e n t r a l space a x i s space w i t h space a n space a n g u l a r space s p e e d space omega subscript 0 space. space N o w comma space t h e space c h i l d space f o l d s space h i s space h a n d s space b a c k space s o space t h a t space m o m e n t space o f space i n e r t i a space b e c o m e s space 3 space t i m e s space t h e space i n i t i a l space v a l u e. space T h e space n e w space a n g u l a r space s p e e d space i s

    A space c h i l d space i s space s tan d i n g space w i t h space h i s space t w o space a r m s space o u t s t r e t c h e d space a t space t h e space c e n t r e space o f space a space t u r n t a b l e space t h a t space i s space r o t a t i n g space a b o u t space i t s space c e n t r a l space a x i s space w i t h space a n space a n g u l a r space s p e e d space omega subscript 0 space. space N o w comma space t h e space c h i l d space f o l d s space h i s space h a n d s space b a c k space s o space t h a t space m o m e n t space o f space i n e r t i a space b e c o m e s space 3 space t i m e s space t h e space i n i t i a l space v a l u e. space T h e space n e w space a n g u l a r space s p e e d space i s

    PhysicsMechanics
    Mechanics
    Physics

    text  A solid cylinder of mass  end text 20 kg text  and radius  end text 20 cm text  rotates about its axis with a angular speed  end text
100 text  rad  end text s to the power of negative 1 end exponent. text The angular momentum of the cylinder about its axis is  end text

    text  A solid cylinder of mass  end text 20 kg text  and radius  end text 20 cm text  rotates about its axis with a angular speed  end text
100 text  rad  end text s to the power of negative 1 end exponent. text The angular momentum of the cylinder about its axis is  end text

    PhysicsMechanics
    Mechanics
    Physics

    text  A circular platform is mounted on a vertical frictionless axle. Its radius is  end text r equals 2 m text  and its moment  end text
text  of inertia  end text straight I equals 200 kgm squared text  . It is initially at rest. A  end text 70 kg text  man stands on the edge of the platform and  end text
text  begins to walk along the edge at speed  end text v subscript 0 equals 1 ms to the power of negative 1 end exponent text relative to the ground. The angular velocity  end text
text  of the platform is  end text

    text  A circular platform is mounted on a vertical frictionless axle. Its radius is  end text r equals 2 m text  and its moment  end text
text  of inertia  end text straight I equals 200 kgm squared text  . It is initially at rest. A  end text 70 kg text  man stands on the edge of the platform and  end text
text  begins to walk along the edge at speed  end text v subscript 0 equals 1 ms to the power of negative 1 end exponent text relative to the ground. The angular velocity  end text
text  of the platform is  end text

    PhysicsMechanics
    parallel
    Mechanics
    Physics

    text  A particle of mass  end text 1 kg text  is moving along the line  end text straight y equals straight x plus 2 text  (here  end text straight x text  and  end text straight y text  are in  end text straight m text  ) with speed  end text 2 straight m divided by straight s
text  The magnitude of angular momentum of the particle about origin is:  end text

    text  A particle of mass  end text 1 kg text  is moving along the line  end text straight y equals straight x plus 2 text  (here  end text straight x text  and  end text straight y text  are in  end text straight m text  ) with speed  end text 2 straight m divided by straight s
text  The magnitude of angular momentum of the particle about origin is:  end text

    PhysicsMechanics
    Mechanics
    Physics

    A space h o l l o w space s t r a i g h t space t u b e space o f space l e n g t h space l space a n d space m a s s space m space c a n space t u r n space f r e e l y space a b o u t space i t s space c e n t r e space left parenthesis f i x e d right parenthesis space o n space a space s m o o t h space h o r i z o n t a l space t a b l e. space A n o t h e r space s m o o t h space u n i f o r m space r o d space o f space s a m e space l e n g t h space a n d space m a s s space i s space f i t t e d space i n t o space t h e space t u b e space s o space t h a t space t h e i r space c e n t r e s space c o i n c i d e. space T h e space s y s t e m space i s space s e t space i n space m o t i o n space w i t h space a n space i n i t i a l space a n g u l a r space v e l o c i t y space omega subscript 0 space space. space T h e space a n g u l a r space v e l o c i t y space o f space t h e space r o d space a t space a n space i n s tan t space w h e n space t h e space r o d space s l i p s space o u t space o f space t h e space t u b e space i s colon

    A space h o l l o w space s t r a i g h t space t u b e space o f space l e n g t h space l space a n d space m a s s space m space c a n space t u r n space f r e e l y space a b o u t space i t s space c e n t r e space left parenthesis f i x e d right parenthesis space o n space a space s m o o t h space h o r i z o n t a l space t a b l e. space A n o t h e r space s m o o t h space u n i f o r m space r o d space o f space s a m e space l e n g t h space a n d space m a s s space i s space f i t t e d space i n t o space t h e space t u b e space s o space t h a t space t h e i r space c e n t r e s space c o i n c i d e. space T h e space s y s t e m space i s space s e t space i n space m o t i o n space w i t h space a n space i n i t i a l space a n g u l a r space v e l o c i t y space omega subscript 0 space space. space T h e space a n g u l a r space v e l o c i t y space o f space t h e space r o d space a t space a n space i n s tan t space w h e n space t h e space r o d space s l i p s space o u t space o f space t h e space t u b e space i s colon

    PhysicsMechanics
    Mechanics
    Physics

    The moment of inertia of a hollow sphere of mass M having internal and external radii R and 2R about an axis passing through its centre and perpendicular to its plane is

    The moment of inertia of a hollow sphere of mass M having internal and external radii R and 2R about an axis passing through its centre and perpendicular to its plane is

    PhysicsMechanics
    parallel
    Mechanics
    Physics

    Two circular loops A and B are made of the same wire and their radii are in the ratio 1:n.Their moments of inertia about the axis passing through the centre and perpendicular to their planes are in the ratio 1:m. The relation between m and n is

    Two circular loops A and B are made of the same wire and their radii are in the ratio 1:n.Their moments of inertia about the axis passing through the centre and perpendicular to their planes are in the ratio 1:m. The relation between m and n is

    PhysicsMechanics
    Mechanics
    Physics

    Four thin metal rods, each of mass M and length L, are welded to form a square ABCD as shown in figure. The moment of inertia of the composite structure about a line which bisects rods AB and CD is

    Four thin metal rods, each of mass M and length L, are welded to form a square ABCD as shown in figure. The moment of inertia of the composite structure about a line which bisects rods AB and CD is

    PhysicsMechanics
    Mechanics
    Physics

    Two rings of the same radius R and mass M are placed such that their centres coincide and their planes are perpendicular to each other. The moment of inertia of the system about an axis passing through the common centre and perpendicular to the plane of one of the rings is

    Two rings of the same radius R and mass M are placed such that their centres coincide and their planes are perpendicular to each other. The moment of inertia of the system about an axis passing through the common centre and perpendicular to the plane of one of the rings is

    PhysicsMechanics
    parallel
    Mechanics
    Physics

    A uniform circular disc of radius 'R' lies in the X-Y plane with the centre coinciding with the origin. The moment of inertia about an axis passing through a point on the X-axis at a distance x = 2R and perpendicular to the X-Y plane is equal to its moment of inertia about an axis passing through a point on the Y-axis at a distance y = d and parallel to the X-axis in the X-Y plane. The value of 'd' is

    A uniform circular disc of radius 'R' lies in the X-Y plane with the centre coinciding with the origin. The moment of inertia about an axis passing through a point on the X-axis at a distance x = 2R and perpendicular to the X-Y plane is equal to its moment of inertia about an axis passing through a point on the Y-axis at a distance y = d and parallel to the X-axis in the X-Y plane. The value of 'd' is

    PhysicsMechanics
    Mechanics
    Physics

    A thin rod of length L and mass M is bent at the middle point O at an angle of 0 60 . The moment of inertia of the rod about an axis passing through O and perpendicular to the plane of the rod will be

    A thin rod of length L and mass M is bent at the middle point O at an angle of 0 60 . The moment of inertia of the rod about an axis passing through O and perpendicular to the plane of the rod will be

    PhysicsMechanics
    Mechanics
    Physics

    Four identical solid spheres each of mass M and radius R are fixed at four corners of a light square frame of side length 4R such that centres of spheres coincide with corners of square. The moment of inertia of 4 spheres about an axis perpendicular to the plane of frame and passing through its centre is

    Four identical solid spheres each of mass M and radius R are fixed at four corners of a light square frame of side length 4R such that centres of spheres coincide with corners of square. The moment of inertia of 4 spheres about an axis perpendicular to the plane of frame and passing through its centre is

    PhysicsMechanics
    parallel

    card img

    With Turito Academy.

    card img

    With Turito Foundation.

    card img

    Get an Expert Advice From Turito.

    Turito Academy

    card img

    With Turito Academy.

    Test Prep

    card img

    With Turito Foundation.