Title 1. Low of motion (N.R. ) E.pdf ✅

Q.6 In the given arrangement, strings and pulleys are light and all surface are frictionless. Assuming at t = 0, system is released from rest, find the speed of block A (in decameter/sec) at t = 2 sec. 4m A B C m m D 2m Sol. [1] The system can be redraw as 4m A 4m  a = 8m 4mg = 2 g = 5m/s2  v = u + at = 2 × 5 = 10 m/s Q.7 In the system shown in figure all surfaces are frictionless while pulley and strings are light. Mass of block A is 2m while that of B is 'm'. Acceleration of block 'B' (in cm/s2 ) immediately after system is released from rest minus 320 cm/s2 is (Take g = 981 cm/s2 ). m 2 m B A Sol. [7] T = 2 ma mg – T = ma  a = g/3. Q.8 In the arrangement shown in figure end 'A' of light inextensible string is pulled with constant velocity v = 6 m/s. The velocity of block 'B' is (in m/s) - Sol. [2] According to principle of virtual work T. v = 3T . vB  vB = v/3 Q.9 Figure shows a string passing through two fixed pulley P1 and P3 and a pulley P2 free to move vertically. One end of string is attached with ring A. Velocity of pulley P2 at the instant shown is (in m/s) - P2 60o 1 m/s B P3 A m/s 3 14 60o P1 Sol. [4] By constraint relation VA sin 60o = P2 V (1 + cos 60o) + VB  P2 V = 4 m/s. Q.10 A block of mass 1 kg is just fit in a groove in a platform kept horizontally. Groove is along + ve x-axis. The platform is given acceleration v (= 6 m/s) B A