Recent questions tagged unit5

A hollow sphere of radius R rests on a surface of finite coefficient of friction, A point object of mass m moved horizontally and his the sphere at a height of $\large\frac{R}{2}$ above its centre. The collision is completely inelastic. Which of the following is/are correct ? 1) total linear momentum of the system is not conserved 2) total angular momentum about centre of mass of the system remains constant. 3) the sphere gets finite angular velocity immediately after collision. 4) the sphere moves with finite speed immediately after collision.

asked Dec 9, 2013 by meena.p

0 answers

The torque $\overrightarrow{z}$ on a body about a given point is found to be $ \overrightarrow{A} \times \overrightarrow{L}$ where $\overrightarrow {A}$ is a constant vector and $\overrightarrow{L}$ is angular momentum about that point . From this it follows that. 1) $\large\frac{dL}{dt}$ is perpendicular to $\overrightarrow {L}$ at all times 2) the component of $\overrightarrow {L}$ in the direction of $\overrightarrow{A}$ does not change with time. 3) the magnitude of $\overrightarrow {L}$ does not change with time. 4) $\overrightarrow {L}$ does not change with time. Which of the following is correct?

asked Dec 9, 2013 by meena.p

1 answer

A ring without slipping on a horizontal surface. At any instant , its position is as shown in figure. 1) Section ABC has greater kinetic energy than ADC 2) Secion BC has same kinetic energy as section DA 3) Secion BC has greater kinetic energy than section DA 4) the Secion AB,BC,CD and DA have same kinetic energy Which of the following is correct?

asked Dec 9, 2013 by meena.p

0 answers

A ring rolls without slipping on the ground. Its centre C moves with a constant speed u. P is any point on the ring. The speed of P with respect to the ground is V. 1) $0 \leq v \leq 2u$ 2) $v=u $, if CP horizontal 3) $v=u$ if CP makes an angle of $60^{\circ}$ with the horizontal and p is below the horizontal level of C 4) $v= \sqrt 2 u$ if CP is horizontal Which of the following is correct?

asked Dec 9, 2013 by meena.p

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A thin uniform rod of mass m and length l is rotate about its upper end. When it is at rest, it receives an impulse J at its lowest point normal to its length. Immediately after impact, 1) the angular mometum of the rod is $JL$ 2) the angular velocity of the rod is $\large\frac{3J}{ml}$ 3) the kinetic energy of the rod is $\large\frac{3J^2}{2m}$ 4) the linear velocity of the midpoint of the rod is $\large\frac{3J}{3m}$ Which of the following is correct?

asked Dec 9, 2013 by meena.p

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The motion of a sphere moving on a rough horizontal surface change from pure sliding (without rolling) to pure rolling (with out slipping) . In this process, the force of friction. 1) initially acts opposite to the direction of motion and later in the direction of motion. 2) causes linear retardation 3) causes angular acceleration 4) stops acting when pure rolling begins. Which of the following is correct?

asked Dec 9, 2013 by meena.p

1 answer

Two identical spheres A and B are free to move and to rotate about their centres. They are given the same impacts J. The line of action of the impulses pass through the centre of A and away from the centre of B.

asked Dec 9, 2013 by meena.p

0 answers

A constant external torque acts for a very brief $\Delta t$ on a rotating system having moment of inertia I.

asked Dec 8, 2013 by meena.p

0 answers

Two horizontal discs of different radius are free to rotate about their central vertical axes. One is given some angular velocity, the other is stationary . Their rims are now brought in contact. There is friction between the rims.

asked Dec 8, 2013 by meena.p

0 answers

A horizontal disc rotates freely about a vertical axis through its centre. A ring, having the same mass and radius as the disc , is now gently placed on the disc. After some time, the two rotate with a common angular velocity. 1) some friction exits between the disc and the ring 2) the angular mometum of disc plus ring is conserved. 3) the final common angular velocity is $\large\frac{2}{3}$ rd of the initial angular velocity of disc. 4) $\large\frac{2}{3}$ rd of the initial kinetic energy is converted to heat. Which of the following is correct?

asked Dec 8, 2013 by meena.p

1 answer

A man standing on a platform holds weight in his out stretched arms. The system rotates freely about a central vertical axis. If he now draws the weights inwards close to his body. 1) the angular velocity of the system will decrease 2) the angular momentum of the system will decrease. 3) the kinetic energy of the system will increase 4) he will have to expend some energy to draw the weights in Which of the following is correct?

asked Dec 8, 2013 by meena.p

0 answers

A man spinning in free space changes of his body e.g by spreading his arms and curling up. By doing this, he can change his 1) moment of inertia 2) angular momentum 3) angular velocity 4) rotational kinetic energy in this Which of the following is correct?

asked Dec 8, 2013 by meena.p

2 answers

A body is in equilibrium under the influence of a number of a forces. Each force has a different line of action. The minimum number of forces required is

asked Dec 8, 2013 by meena.p

0 answers

When slightly different weights are placed on the two pane of a beam balance, the beam comes to rest at an angle with the horizontal. The beam is supported at a single point P by a pivot.

asked Dec 8, 2013 by meena.p

0 answers

A particle of mass m is travelling with a constant velocity $\overrightarrow {V} =V_0 \hat i$ along the line $y=b,z=0$. Let $dA$ be the area swept out by the position vector from the origin to the particle in time at end L be the magnitude of angular momentum of particle about orgin at any time t. Then 1) L= constant 2) $\large\frac{dA}{dt}=\frac{L}{m}$ 3) $\large\frac{dA}{dt}= \frac{2L}{m}$ 4) $\large\frac{dA}{dt}=\frac{L}{2m}$ Which of the following is correct?

asked Dec 8, 2013 by meena.p

1 answer

A spherical body of radius R rolls on a horizontal surface with linear velocity $V$. Let $L_1$ and $L_2$ be the magnitude of angular momentum of the body about the centre of mass and point of contact P respectively. a) $L_2=L_1$ if radius of gyration $k=R$ b) $L_2=2L_1$ for all cases. c) $L_2 > 2L_1$ if radius of gyration $K < R$ d) $L_1> L_2$ if radius of gyration $ K > R$ Which of the following is correct?

asked Dec 8, 2013 by meena.p

1 answer

A disc can roll without slipping without applying any external force on a 1) rough inclind plane 2) smooth inclined plane 3) rough horizontal surface 4) smooth horizontal surface Which of the following is correct?

asked Dec 8, 2013 by meena.p

0 answers

Which of the following statements are correct for a spherical body rolling without slipping on a rough horizontal ground at rest.

asked Dec 6, 2013 by meena.p

1 answer

A cubical block of side a is moving with a velocity v on a smooth horizontal plane as shown. It hits a ridge at point O. The angular speed of the block when it hits O is

asked Dec 6, 2013 by meena.p

1 answer

For toppling of the regular hexagon shown. the coefficient of friction must be

asked Dec 6, 2013 by meena.p

1 answer

A block with a square base measuring $a \times a$ and height h, is placed on an inclined plane. The coefficient of friction is $\mu$. The angle of inclination $(\theta)$ of the plane is gradually increased. The block will

asked Dec 6, 2013 by meena.p

1 answer

A uniform cube of side 'a' and mass 'm' rests on a rough horizontal table. A horizontal force 'F' is applied normal to one of the faces at a point that is directly above at a height $\large\frac{3a}{4}$ above the base. The minimum value of 'F' for which the cube begins to lilt about the edge is (assume cube does not slide)

asked Dec 6, 2013 by meena.p

1 answer

A cylinder rolls without slipping on a rough horizontal floor, its centre of mass moving with speed v. It makes an elastic collision with a smooth vertical wall. After impact

asked Dec 5, 2013 by meena.p

1 answer

A circular wooden loop of mass m and radius R rest on a flat horizontal friction less surface. A bullet, also of mass m, and moving with a velocity V, strikes the loop and gets embedded in it. The thickness of the loop is much smaller than R. The angular velocity with which the system angular velocity with which the system rotates just after the bullet strikes the loop is

asked Dec 5, 2013 by meena.p

1 answer

A body is given translational velocity and kept on a surface that has sufficient friction. Then

asked Dec 5, 2013 by meena.p

1 answer

A sphere is released on a smooth inclined plane from the top. When it moves down its angular momentum is

asked Dec 5, 2013 by meena.p

1 answer

A sphere S rolls without slipping, moving with constant speed on a plank p. The friction between the upper surface of P and the sphere is sufficient to prevent slipping, While the lower surface of p is smooth and rest on the ground. Initially P is fixed to the ground by a pin N. If N is suddenly removed :

asked Dec 5, 2013 by meena.p

1 answer

A thin spherical shell lying on a rough horizontal surface is hit by a cue in such a way that the line of action passes through the centre of the shell. As a result the shell starts moving with a linear speed V with out any initial angular velocity. Find the speed of the shell after it starts pure rolling on the surface .

asked Dec 5, 2013 by meena.p

1 answer

A uniform wheel of radius R is set into rotation about its axis at an angular speed w.This rotating wheel is now placed on a rough horizontal surface with its axis horizontal. Because of friction at the contact , the wheel accelerated forward and its rotation decelerates till the wheel starts pure rolling on the surfaces . Find the linear speed of the wheel after it starts pure rolling.

asked Dec 5, 2013 by meena.p

1 answer

Figure shows a rough track, a portion of which is in the form of a cylinder of radius R. with what minimum linear speed should a sphere of radius r be set rolling on the horizontal part so that it completes goes round the circle on the cylindrical part?

asked Dec 5, 2013 by meena.p

1 answer

A small spherical ball is released from a point at a height h on a rough track. Assuming that it does not slip any where , find its linear speed when it rolls on the horizontal part of the track.

asked Nov 29, 2013 by meena.p

1 answer

A small object density rolls up a curved surface with an initial velocity V. It reaches up to a maximum height of $ \large\frac{3V^2}{4g}$ with respect to the initial position. The object is

asked Nov 29, 2013 by meena.p

1 answer

A uniform circular disc of radius r is placed on a rough horizontal surface and given a linear $w_0$ as shown. The disc com,es to rest after moving some distance to the right. It follows that

asked Nov 29, 2013 by meena.p

2 answers

A solid sphere is placed rotating with its center initially at rest in a corner as shown. (a) and (b) . Coefficient of friction between all surfaces and sphere is $\large\frac{1}{3}$ Find the ratio of friction forces $\large\frac{fa}{fb}$ by ground in situations (a) and (b)

asked Nov 29, 2013 by meena.p

1 answer

A solid sphere of mass m is lying at rest on a rough horizontal surface. The coefficient of friction between the ground and sphere is $\mu$. The maximum value of F, so that the sphere will not slip is equal to

asked Nov 29, 2013 by meena.p

2 answers

A ring, cylinder and solid sphere are placed on the top of a rough incline on which the sphere can just roll with out slipping. When all of them are released at the same instant from the same position, then

asked Nov 29, 2013 by meena.p

1 answer

A hollow smooth uniform sphere A of mass 'm' roll without sliding on a smooth horizontal surface. It collides elastically and head on with another stationary solid sphere B of the same mass m and same radius. The ratio of kinetic energy of 'B' to that of 'A' just after the collision is

asked Nov 29, 2013 by meena.p

1 answer

As shown in the figure , auniform disc of mass m is rolling without slipping with an angular velocity w. The portion AB is rough and BC is smooth. When it crosses the point B disc will be in

asked Nov 29, 2013 by meena.p

1 answer

A body of mass m and radius r is rotated with angular velocity w as shown. and then kept on a surface that has sufficient friction. then the body will move

asked Nov 29, 2013 by meena.p

1 answer

A uniform disc is performing pure rolling on a smooth stationary surface with constant angular velocity. At any instant, for the lower most point of the disc

asked Nov 29, 2013 by meena.p

1 answer

An object of mass M and Radius R is performing pure rolling. motion on smooth horizontal surface under the action of a constant force F. The object may be

asked Nov 29, 2013 by meena.p

1 answer

If a spherical ball rolls with out slipping, the fraction of its total energy associated with rotation is

asked Nov 29, 2013 by meena.p

1 answer

A yo-yo placed on a rough horizontal surface and a constant force F, less than its weight , pulls it vertically . Due to this

asked Nov 29, 2013 by meena.p

1 answer

A disc of radius R rolls on a horizontal ground with linear acceleration $'a'$ and angular acceleration $' \alpha '$ as shown. The magnitude of the acceleration $'\alpha'$ of point P at an instant , when its linear velocity is V and angular velocity is $w$ will be,

asked Nov 29, 2013 by meena.p

1 answer

Which of the following statement(s) is /are correct for a spherical body rolling with out slipping on a rough horizontal ground at rest.

asked Nov 29, 2013 by meena.p

1 answer

A disc is pulled by a force F acting at a point above the centre of mass of the disc. The direction of frictional force f acting on the disc pushed on a rough surface will be represented by

asked Nov 29, 2013 by meena.p

1 answer

A disc can roll without slipping , with out applying any external force on a 1) rough inclined plane 2) smooth inclined plane 3) rough horizontal surface 4) smooth horizontal surface

asked Nov 29, 2013 by meena.p

1 answer

A thin string is wrapped several times around a cylinder kept on a rough horizontal surface. A boy standing at a distance l from the cylinder draws the string towards him as shown. The cylinder rolls without slipping . The length of the string passed through the hand of the boy while the cylinder reaches his hand is

asked Nov 29, 2013 by meena.p

1 answer

Consider a disc rolling with out slipping on a horizontal surface at a speed V as shown in figure. 1) the speed of the particle at A is 2V. 2) the speed of the particle and B,C and D is equal to V 3) The speed of C is zero and the speed of B is $\sqrt 2$ V 4) the speed of 0 is less then the speed of V which is the correct answer?

asked Nov 29, 2013 by meena.p

1 answer

Angular momentum of the particle rotating with a central force is constant due to

asked Nov 28, 2013 by meena.p

1 answer

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Two identical spheres A and B are free to move and to rotate about their centres. They are given the same impacts J. The line of action of the impulses pass through the centre of A and away from the centre of B.

A constant external torque acts for a very brief $\Delta t$ on a rotating system having moment of inertia I.

Two horizontal discs of different radius are free to rotate about their central vertical axes. One is given some angular velocity, the other is stationary . Their rims are now brought in contact. There is friction between the rims.

A man spinning in free space changes of his body e.g by spreading his arms and curling up. By doing this, he can change his 1) moment of inertia 2) angular momentum 3) angular velocity 4) rotational kinetic energy in this Which of the following is correct?

A body is in equilibrium under the influence of a number of a forces. Each force has a different line of action. The minimum number of forces required is

When slightly different weights are placed on the two pane of a beam balance, the beam comes to rest at an angle with the horizontal. The beam is supported at a single point P by a pivot.

A disc can roll without slipping without applying any external force on a 1) rough inclind plane 2) smooth inclined plane 3) rough horizontal surface 4) smooth horizontal surface Which of the following is correct?

Which of the following statements are correct for a spherical body rolling without slipping on a rough horizontal ground at rest.

A cubical block of side a is moving with a velocity v on a smooth horizontal plane as shown. It hits a ridge at point O. The angular speed of the block when it hits O is

For toppling of the regular hexagon shown. the coefficient of friction must be

A block with a square base measuring $a \times a$ and height h, is placed on an inclined plane. The coefficient of friction is $\mu$. The angle of inclination $(\theta)$ of the plane is gradually increased. The block will

A cylinder rolls without slipping on a rough horizontal floor, its centre of mass moving with speed v. It makes an elastic collision with a smooth vertical wall. After impact

A body is given translational velocity and kept on a surface that has sufficient friction. Then

A sphere is released on a smooth inclined plane from the top. When it moves down its angular momentum is

Figure shows a rough track, a portion of which is in the form of a cylinder of radius R. with what minimum linear speed should a sphere of radius r be set rolling on the horizontal part so that it completes goes round the circle on the cylindrical part?

A small spherical ball is released from a point at a height h on a rough track. Assuming that it does not slip any where , find its linear speed when it rolls on the horizontal part of the track.

A small object density rolls up a curved surface with an initial velocity V. It reaches up to a maximum height of $ \large\frac{3V^2}{4g}$ with respect to the initial position. The object is

A uniform circular disc of radius r is placed on a rough horizontal surface and given a linear $w_0$ as shown. The disc com,es to rest after moving some distance to the right. It follows that

A solid sphere is placed rotating with its center initially at rest in a corner as shown. (a) and (b) . Coefficient of friction between all surfaces and sphere is $\large\frac{1}{3}$ Find the ratio of friction forces $\large\frac{fa}{fb}$ by ground in situations (a) and (b)

A solid sphere of mass m is lying at rest on a rough horizontal surface. The coefficient of friction between the ground and sphere is $\mu$. The maximum value of F, so that the sphere will not slip is equal to

A ring, cylinder and solid sphere are placed on the top of a rough incline on which the sphere can just roll with out slipping. When all of them are released at the same instant from the same position, then

A hollow smooth uniform sphere A of mass 'm' roll without sliding on a smooth horizontal surface. It collides elastically and head on with another stationary solid sphere B of the same mass m and same radius. The ratio of kinetic energy of 'B' to that of 'A' just after the collision is

As shown in the figure , auniform disc of mass m is rolling without slipping with an angular velocity w. The portion AB is rough and BC is smooth. When it crosses the point B disc will be in

A body of mass m and radius r is rotated with angular velocity w as shown. and then kept on a surface that has sufficient friction. then the body will move

A uniform disc is performing pure rolling on a smooth stationary surface with constant angular velocity. At any instant, for the lower most point of the disc

An object of mass M and Radius R is performing pure rolling. motion on smooth horizontal surface under the action of a constant force F. The object may be

If a spherical ball rolls with out slipping, the fraction of its total energy associated with rotation is

A yo-yo placed on a rough horizontal surface and a constant force F, less than its weight , pulls it vertically . Due to this

A disc of radius R rolls on a horizontal ground with linear acceleration $'a'$ and angular acceleration $' \alpha '$ as shown. The magnitude of the acceleration $'\alpha'$ of point P at an instant , when its linear velocity is V and angular velocity is $w$ will be,

Which of the following statement(s) is /are correct for a spherical body rolling with out slipping on a rough horizontal ground at rest.

A disc is pulled by a force F acting at a point above the centre of mass of the disc. The direction of frictional force f acting on the disc pushed on a rough surface will be represented by

A disc can roll without slipping , with out applying any external force on a <br> 1) rough inclined plane <br> 2) smooth inclined plane <br> 3) rough horizontal surface <br> 4) smooth horizontal surface

Angular momentum of the particle rotating with a central force is constant due to