Physics Objective type question bank -4

If I, a and t are the moment of inertia, angular acceleration and torque respectively of a body rotating about any axis with angular velocity w, then
(CPMT 82)
(a) t = Ia (b) t = Iw
(c) I = tw (d) a = Iw
Answer: (a)

The moment of inertia of a circular ring about an axis passing through its centre and normal to its plane is 200 gm ´ cm2. then its moment of inertia about a diameter is (PMT 87 MP)
(a) 400 gm ´ cm2 (b) 300 gm ´ cm2
(c) 200 gm ´ cm2 (d) 100 gm ´ cm2
Answer: (d)
Two particles A and B, initially at rest, moves towards each other under a mutual force of attraction. At the instant when the speed of A is u and the speed of B is
2 u, the speed of centre of mass is, (IIT 82)
(a) Zero (b) u
(c) 1.5 u (d) 3 u
Answer: (a)
A body of M.I. 3 kg m2 rotating with an angular velocity 2 rad/s has the same K.E. as a mass of 12 kg moving with a velocity of (MH-CET 99)
(a) 1 m/s (b) 2 m/s
(c) 4 m/s (d) 8 m/s
Answer: (a)
Moment of inertia of a disc about the tangent parallel to its plane is I. The moment of inertia of the disc tangent and perpendicular to its plane is (MH-CET 2005)
(a) (b)
(c) (d)
Answer: (d)
The moment of inertia of a disc about its geometrical axis is I. then its M.I. about its diameter will be
(a) I (b) 2I
(c) (d)
Answer: (c)
A particle moves for 20 s with velocity 3 m/s and then moves with velocity 4 m/s for another 20 s and finally moves with velocity 5 m/s for next 20 s. what is the average velocity of the particle? (MHT-CET-2004)
(a) 3 m/s (b) 4 m/s
(c) 5 m/s (d) Zero
Answer: (b)
The term moment of momentum is called
(C.P.M.T.74, MH-CET 99)
(a) Momentum (b) Force
(c) Torque (d) Angular momentum
Answer: (d)
When a mass is rotating in a plane about a fixed point its angular momentum is directed along.
(NCERT 82, MNR 87, MP 86)
(a) The radius
(b) The tangent to orbit
(c) The line at an angle of 45° to the plane of rotation
(d) The axis of rotation
Answer: (d)
A mass M is moving with a constant velocity parallel to the X-axis. Its angular momentum with respect to the origin
(a) Is zero
(b) Remains constant
(c) Goes on increasing
(d) Goes on decreasing
Answer: (b)