JEE Physics System Of Particles and Rotational Motion MCQs Set C

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: A

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

Question. A couple produces
(a) Purely rotational motion
(b) No motion
(c) Linear and rotational motion
(d) Purely linear motion

Answer: A

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: A

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: A

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: A

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: A

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: A