JEE Physics System Of Particles and Rotational Motion MCQs Set C

Question:  Four identical thin rods each of mass M and length l, form a square frame. Moment of inertia of this frame about an axis through the centre of the square and perpendicular to its plane is

• a)

  

• b)

  

• c)

  

• d)

  

Answer:

Question:  The moment of inertia of a uniform circular disc of radius R and mass M about an axis passing from the edge of the disc and normal to the disc is

• a)

  

• b)

  

• c)

  

• d)

  

Answer:

Question:

• a)

  

• b)

  

• c)

  

• d)

  

Answer:

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

• a) Aluminium at interior and iron surround to it
• b) Iron at interior and aluminium surround to it
• c) Using iron and aluminium layers in alternate order
• d) Sheet of iron is used at both external surface and aluminium sheet as interna layers

Answer: Aluminium at interior and iron surround to it

Question: The ratio of the radii of gyration of a circular disc about a tangential axis in the plane of the disc and of a circular ring of the same radius about a tangential axis in the plane of the ring is

• a)

  

• b)

  

• c) 2 : 3
• d) 2 : 1

Answer:

Question:

• a) F₁+ F₂
• b) F₁- F₂
• c)

  

• d) None of this

Answer: F₁+ F₂

Question: When a mass is rotating in a plane about a fixed point, its angular momentum is directed along

• a) A line perpendicular to the plane of rotation
• b) The line making an angle of 45° to the plane of rotation
• c) The tangent to the orbit
• d) The radius

Answer: A line perpendicular to the plane of rotation

Question: The reduced mass of two particles having masses m and 2m is

• a)

  

• b)

  

• c) 3m
• d) 2m

Answer:

Question:

• a)

  

• b)

  

• c)

  

• d)

  

Answer:

Question: A couple produces

• a) Purely rotational motion
• b) No motion
• c) Linear and rotational motion
• d) Purely linear motion

Answer: Purely rotational motion

Question:

• a) t = 1 s
• b) t = 2 s
• c) t = 0.2 s
• d) t = 0.25 s

Answer: t = 1 s

Question:  The angular speed of a fly-wheel making 120 revolutions/minute is

• a)

  

• b)

  

• c)

  

• d)

  

Answer:

Question:

• a) 100
• b) 120
• c) 60
• d) 40

Answer: 100

Question:  A wheel having moment of inertia 2 kgm² about its vertical axis, rotates at the rate of 60 rpm about this axis. The torque which can stop the wheel’s rotation in one minute would be

• a)

  

• b)

  

• c)

  

• d)

  

Answer:

Question: Two bodies have their moments of inertia / and 2/ respectively about their axis of rotation. If their kinetic energies of rotation are equal, their respective angular momenta will be in the ratio

• a)

  

• b)

  

• c) 1 : 2
• d) 2 : 1

Answer:

Question:

• a)

  

• b)

  

• c)

  

• d)

  

Answer:

Question: A particle of mass m moves in the XY plane with a velocity v along the straight line AB. If the angular momentum of the particle with respect to origin O is L_A, when it is at A and L_B when it is at B, then

• a) L_A = L_B
• b) The relationship between L_A and L_B depends upon the slope of the line AB
• c) None of these
• d) L_A< L_B

Answer:  L_A = L_B

Question:

• a)

  

• b)

  

• c)

  

• d)

  

Answer:

Question:

• a)

  

• b)

  

• c)

  

• d)

  

Answer:

Question:

• a) Zero
• b)

  

• c)

  

• d)

  

Answer: Zero

More Questions..................................

Question:

• a)

  

• b)

  

• c)

  

• d)

  

Answer:

Question: A circular platform is mounted on a frictionless vertical axle. Its radius R = 2 m and its moment of inertia about the axle is 200 kg m². It is initially at rest. A 50 kg man stands on the edge of the platform and begins to walk along the edge at the speed of 1 ms^–1 relative to the ground. Time taken by the man to complete one revolution is

• a)

  

• b)

  

• c)

  

• d)

  

Answer:

Question:

• a)

  

• b)

  

• c)

  

• d)

  

Answer:

Question:

• a)

  

• b)

  

• c)

  

• d)

  

Answer:

Question:

• a)

  

• b)

  

• c)

  

• d)

  

Answer:

Question:

• a) Angular momentum
• b) Linear momentum
• c) Kinetic energy
• d) Potential energy

Answer: Angular momentum

Question:

• a)

  

• b)

  

• c)

  

• d) None of these

Answer:

Question:

• a) Disc
• b) Ring
• c) Hollow sphere
• d) Solid sphere

Answer: Disc

Question: A solid spherical ball rolls on a table. Ratio of its rotational kinetic energy to total kinetic energy is (1)

• a)

  

• b)

  

• c)

  

• d)

  

Answer:

Question: A hollow cylinder and a solid cylinder are rolling without slipping down an inclined plane, then which of these reaches earlier?

• a) Solid cylinder
• b) Both simultaneously
• c) Hollow cylinder
• d) Can’t say anything

Answer: Solid cylinder

Question: A disc is rolling such that the velocity of its centre of mass is v_cm. Which one will be correct?

• a) The velocity of highest point is 2 v_cm and point of contact is zero
• b) The velocity of highest point is v_cm and point of contact is v_cm
• c) The velocity of highest point is 2v_cm and point of contact is v_cm
• d) The velocity of highest point is 2v_cm and point of contact is 2v_cm

Answer:  The velocity of highest point is 2 v_cm and point of contact is zero

Question: A solid sphere of radius R is placed on a smooth horizontal surface. A horizontal force F is applied at height h from the lowest point. For the maximum acceleration of centre of mass, which is correct?

• a) Centre of mass has same acceleration in each case
• b) h = 0
• c) h = 2R
• d) h = R

Answer:  Centre of mass has same acceleration in each case

Question: A point P is the contact point of a wheel on ground which rolls on ground without slipping. The value of displacement of the point P when wheel completes half of rotation (If radius of wheel is 1 m)

• a)

  

• b)

  

• c)

  

• d) 2 m

Answer:

Question:  A solid cylinder of mass M and radius R rolls without slipping down an inclined plane of length L and height h. What is the speed of its centre of mass when the cylinder reaches its bottom?

• a)

  

• b)

  

• c)

  

• d)

  

Answer:

Question:  A solid cylinder and a hollow cylinder, both of the same mass and same external diameter are released from the same height at the same time on a inclined plane. Both roll down without slipping. Which one will reach the bottom first?

• a) Solid cylinder
• b) Hollow cylinder
• c) Both together
• d) Both together only when angle of inclination of plane is 45º

Answer:  Solid cylinder

Question:

• a) Converts translational energy to rotational energy
• b) Decreases the rotational motion
• c) Dissipates energy as heat
• d) Decreases the rotational and translational motion

Answer:  Converts translational energy to rotational energy

Question: A ball rolls without slipping. The radius of gyration of the ball about an axis passing through its centre of mass is K. If radius of the ball be R, then the fraction of total energy associated with its rotational energy will be

• a)

  

• b)

  

• c)

  

• d)

  

Answer:

Question: The moment of inertia of a disc of mass M and radius R about an axis, which is tangential to the circumference of the disc and parallel to its diameter is

• a)

  

• b)

  

• c)

  

• d)

  

Answer:

Question: The ratio of radii of gyration of a circular ring and a circular disc, of the same mass and radius, about an axis passing through their centres and perpendicular to their planes are

• a)

  

• b)

  

• c) 3 : 2
• d) 3 : 1

Answer:

Question:  Two particles which are initially at rest, move towards each other under the action of their internal attraction. If their speeds are v and 2v at any instant, then the speed of centre of mass of the system will be

• a) Zero
• b) 1.5 v
• c) 2 v
• d) v

Answer: Zero