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PHYSICS
I Targe* IIT JEE 2007 Daily Practice Problems CLASS: XI (PQRS) DATE: 30-31/12/200S MAX. TIME: 60 Min. DPP. NO -88 Q. 1 AbaJl ofmass m is attached to the lower end of a light vertical spring of force constant k. The upper end ofthe spring isfixed.The ball is releasedfromrest with the spring at its normal length, and comes to rest again after descending through a distance x. (A) x=mg/k • . . ! • • • ' • 1 (B)x=2mg/k ;; (C) The ball will have no acceleration at the position where it has descended through x/2 (D) The ball will have an upward acceleration equal to g at its lowermost position. Q.2 A block of mass 100 gm attached to a spring of stiffness 100 N/m is lying on a frictionlessflooras shown. The block is moved to compress the spring by 10 cm and released. If the collision with the wall is elastic thetimeperiod ofmotion is (A) 0.2 sec (B)0.1 sec •(C) 0.155 sec (D) 0.133 see Q. 3 A wireframein the shape of an equilateral triangle is hinged at one vertex so that it can swingfreelyin a vertical plane, with the plane of the A always remaining vertical. The side oftheframeis i / v 3 m. The time period in seconds of small oscillations of theframewill be (A)^ Q.4
(B)W2.
(C)^
(D)^
A small bob attached to a light inextensible thread oflength / has a periodic time T when allowed to vibrate as a simple pendulum. The thread is now suspendedfromafixedend 31 O ofa verticalrigidrod oflength — (as infigure).Ifnow the pendulum performs periodic oscillations in this arrangement, the periodictimewill be (A)~-
Q.5
(B) |
(C)T
(D)2T
A body performs simple harmonic oscillations along the straight line ABCDE with C as the midpoint of AE. Its kinetic energies at B and D are each one fourth of its maximum value. IfAE=2R, the distance between B and D is (A)™
(B)^
(C) 1/3 R
<P)V2R
B
C
D
E
Q.6
A particular S.H.M. has an amplitude of A& period T. The magnitude of its velocity and acceleration T/8 seconds after the particle reaches the extreme position would be & - respectively.
Q.7
A spring block system is kept on a horizontal smooth plane as shown AB & CD are two rigid elastic walls. Separation between the block and wall CD is d. What is the maximum velocity that can be imparted to the block, of mass m, towards the wall CD such that time period of the oscillations
(1)
(ii)
under the action of spring force, is 2n4m / k • sec where K is the spring constant ofthe ideal massless spring, Ifthe velocity imparted to the block is twice this maximum valuefindthe time period of oscillations ofthe spring block system.