Question

A block of weight w slides down a smooth inclined plane of slope 37° at a constant speed while the plank b with weight 3w placed on the top of the block

Answer 1

block moves down the plane with constant velocity it means net force is zero...

force due to friction (f) = mgsin@                              (@ is the angle of plane)

net retardation force when body is projected upward is (f+mgsin@)

f = mgsin@ so

net retardation force = 2mgsin@

    ma = mgsin@

    a(retardation) = 2gsin@        .............1

V2 = U2 - 2aS

finally velocity becomes 0 so

 U2 = 2aS

S = U2/2a

   =u2/4gsin@