In the following figure, a weight W is attached to a string wrapped round a solid cylinder of mass M mounted on a frictionless horizontal axle at O.

If the weight starts from rest and falls a distance h, then its speed at that instant is

  • Proportional to R

  • Proportional to 1R

  • Proportional to 1R2

  • Independent of R

A solid cylinder rolls down an inclined plane that has friction sufficient to prevent sliding. The ratio of rotational energy to total kinetic energy is

 

  •   12

  •   13

  •   23

  •   34

A swimmer while jumping into water from a height easily forms a loop in the air, if

  • He pulls his arms and legs in

  • He spreads his arms and legs

  • He keeps himself straight

  • None of the above

Assertion : A ladder is more apt to slip when you are high up on it than when you just begin to climb

Reason : At the high point on a ladder, the torque is large and on climbing up the torque is small

  1. If both the assertion and the reason are true and the reason is a correct explanation of the assertion
  2. If both the assertion and reason are true but the reason is not a correct explanation of the assertion
  3. If the assertion is true but the reason is false
  4. If both the assertion and reason are false
  • 1
  • 2
  • 3
  • 4

An inclined plane makes an angle of 30° with the horizontal. A solid sphere rolling down this inclined plane from rest without slipping has a linear acceleration equal to

 

  •   g3

  •   5g7

  •   2g3

  •   5g14

Which of the following statements is correct?

lisions

  •    Kinetic energy and momentum both are conserved in all types of collisions

  •    Total kinetic energy is not conserved but momentum is conserved in inelastic COI-

  •   Momentum is conserved In elastic collisions but .not in inelastic collisions

  •   Total kinetic energy is conserved in inelastic collisions but momentum is not conserved in elastic collisions

A ball of mass m moving with velocity v0 collides a wall as shown in the figure. After impact, it rebounds with a velocity 34v0. The impulse acting on ball during impact is 

                

 

 

  •   -m2v0 j^

  •   -34mv0 j^

  •   -54mv0 i^

  •   None of these

The figure shows a small wheel fixed coaxially on a bigger one of double the radius. The system rotates about the common axis. The strings supporting A and B do not slip on the wheels. If x and y be the distances traveled by A and B in the same time interval, then

                   

  •   x-2y

  •   x = y

  •   y=2x

  •    none of these

If a gymnast, sitting on a rotating stool, with his arms outstretched, suddenly lowers his hands

  •   the angular velocity increases

  •   his moment of inertia increases

  •   the angular velocity stays constant

  •   the angular momentum increases

Moment of inertia of a uniform circular disc about a diameter is I. Its moment of inertia about an axis perpendicular to its plane and passing through a point on its rim will be

  •   5 I

  •   3 I

  •   6 I

  •   4 I

A disc and a solid sphere of the same radius but different masses roll off on two inclined planes of the same altitude and length. Which one of the two objects gets to the bottom of the plane first?

  •   Disk

  •    Sphere

  •   Both reach at the same time

  •   Depends on their masses

A particle of mass m moves in the XY planewith a velocity of V along the straight line AB. If the angular momentum of the particle about the origin O is Lwhen it is at A and Lwhen it is at B, then

               

  •   LA > LB

  •   LA = LB

  •   The relationship between LA and LB depends upon the slope of the line AB

  •   LA < LB

If rotational kinetic energy is 50 % of translational kinetic energy, then the body is 

  • Ring

  • Cylinder

  • Hollow sphere

  • Solid sphere

Consider a system of two identical particles. One of the particles is at rest and the other has an acceleration a. The centre of mass has an acceleration

  • zero

  • 1/2 a

  • a

  • 2 a

A solid sphere rolls without slipping down a 30° inclined plane. If g = 10 m/s2, the acceleration of the rolling sphere is

  •   5 ms-2

  •   725ms-2

  •   257ms-2

  •   157ms-2

If the equation for the displacement of a particle moving on a circular path is given by θ=2t3+0.5, where θ is in radian and t is in second, then the angular velocity of the particle after 2s is 

  • 8 rad/s

  • 12 rad/s

  • 24 rad /s

  • 36 rad/s

A pan containing a layer of uniform thickness of ice is placed on a circular turntable with its centre coinciding with the centre of the turn table. The turntable is now rotated at a constant angular velocity about a vertical axis passing through its centre and then driving is withdrawn. There is no friction between the table. As the ice melts

  •   the angular velocity of the system decreases

  •   the angular velocity of the system increases

  •   the angular velocity of the system remains unchanged

  •   the moment of inertia of the system decreases

The motion of planets in the solar system is an example of the conservation of

  •   mass

  •   Linear momentum

  •   Angular momentum

  •   Energy

A circular disc is to be made by using iron and aluminium, so that it acquires maximum moment of inertia about its geometrical axis.  It is possible with

  • iron and aluminium layers in alternate order

  • aluminium at interior and iron surrounding it

  • iron at interior and aluminium surrounding it

  • either '1' or '3'

A particle of mass 15 kg has an initial velocity vi = i^ - 2j^ m/s. It collides with another body and the impact time is 0.1 s, resulting in a velocity vf = 6i^ + 4j^ + 5k^ m/s after impact. The average force of impact on the particle is

  •   155i^ + 6j^ + 5k^

  •   155i^ + 6j^ - 5k^

  •   1505i^ - 6j^ + 5k^

  •   1505i^ + 6j^ + 5k^

Two Circular discs A and B are of equal masses and thicknesses but made of metal with densities dA and dB (dA > dB). If their moments of inertia about an axis passing through their centers and perpendicular to circular faces be IA and IB, then

  •   IA = IB

  •   IA > IB

  •   IA<IB

  •   IA  IB

A body is rolling without slipping on a horizontal surface and its rotational kinetic energy is equal to the translational kinetic energy. The body is 

  •   Disc

  •   Sphere

  •   Cylinder

  •   Ring

A wheel with a radius of 20 cm has forces applied to it as shown in the figure. The torque produced by the forces of 4 N at A, 8N at B, 6 N at C, and 9N at D, at the angles indicated, is:
                    

  •   5.4 N-m anticlockwise

  •   1.80 N-m clockwise

  •   2.0 M-m clockwise

  •   3.6 n-m clockwise

The moment of inertia of a thin rectangular plate ABCD of uniform thickness about an axis passing through the centre O and perpendicular to the plane of the plate is 

                            

  •   I1 + I2

  •   I2 + I4

  •   I1 - I3

  •   I1 + I2 + I3 + I4

The centre of a wheel rolling on a plane surface moves with a speed v0. A particle on the rim of the wheel at the same level as the centre will be moving at speed

  •   zero

  •   v0

  •   2v0

  •   2v0

Moment of inertia of a uniform cylinder of mass M, radius R and length l about an axis passing through its center and normal to its axis would be

  •   Ml212

  •   MR22

  •   Ml212 + R24

  •   Ml212 + R22

A particle moves along a circle of radius 20πm with constant tangential acceleration. If the velocity of the particle is 80 m/s at the end of the second revolution after motion has begin, the tangential acceleration is

  • 640 π m/s2

  • 160 π m/s2

  • 40 π m/s2

  • 40 m/s2

If the radius of the earth is suddenly contracted to half of its present value, then the duration of the day will be of

  •   6 hours

  •   12 hours

  •   18 hours

  •   24 hours

A wheel has angular acceleration of 3.0 rad/sec2 and an initial angular speed of 2.00 rad/sec.  In a time of 2 sec it has rotated through an angle (in radian) of 

  • 10               

  • 12

  • 4                 

  • 6

The bob A of a simple pendulum is released when the string makes an angle of 45 with the vertical. It hits another bob B of the same material and the same mass kept at rest on a table. If the collision is elastic

                         

  •   Both A and B rise to the same height

  •   Both A and B come to rest at B

  •   Both A and B move with the same velocity of A

  •   A comes to rest and B moves with the velocity of A

0:0:1


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