A block of mass 15 kg is placed on a long trolley. The coefficien t of static friction between the block and the trolley is 0.18. The trolley accelerates from rest with 0.5 ms^(2) for 20 s and then moves with uniform velocity. Discuss the motion of the block as viewed by (a) a stationary observer on the ground, (b) an observer moving with the trolley.

A block of mass 15 kg is placed on a long trolley. The coefficien t of

1.	A block of mass 15 kg is placed on a long trolley. The coefficien t of static friction between the block and the trolley is 0.18. The trolley accelerates from rest with 0.5 ms^(2) for 20 s and then moves with uniform velocity. Discuss the motion of the block as viewed by (a) a stationary observer on the ground, (b) an observer moving with the trolley.
Answer» Solution : Massof blockm =15 kg accelerationof trolley a=0.5 `ms^(2)` (a)WhenblockmoveswithtrolleyForceactingon blockF= m `=7.5 N` Dueto REACTIN forcewill acton blockdirectionof thisforcewill motiontrolley . Staticfriction willact on blockstaticfrictionactingonblock `f= muR` `=mu mg` Heremaximumstaticfriction(26.46 N)`gt ` forceactingon block(7.5 N) ( b )Whenoberseveris movingwithtrolley.thiswill benon-inertiareferenceframe . Henceto observerblockappearto bestationary.