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a OF Problems 12-14 |, A block of mass M is kept in elevator (lift) whic S MOVing, “PWward with constant acceleration ‘b’ as shown in figure. Initially, elevator at rest. The block is observed By servers A and B, for a time interval t= 0 to t= T. Obseryé gat rest with respect, to elevator and observer A is st ndj, , , , , , , , Bs pe observer A finds that the work done by gravity on the, , - Block is (a) |e??? = (b) Liyjgis |, Z | ; |, J Z a | 1 :, page (4) —5MgbT, , 13 The observer A finds that work done by normal reaction, acting on the block is, , (a) 5 (Me +b) T tse. A) ~S(Mg-+b)7?, , fo =M(s +b)bT? = @) ~>M(g+by67?, 1% ‘According to observer B, 4 (a) The work done by gravity on the block is zero, , (b) The work done by normal reaction on the block is zero, , (c) The work done by pseudo force on the block is zero, (d) All the above are correct |