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.

Explanation

Mass of block m =15 kg
acceleration of trolley a= 0.5 `ms^(2)`
(a) When block moves with trolley Force acting on block F= m
`=7.5 N`
Due to reactin force will act on block direction of this force will motion trolley . Static friction will act on block static friction acting on block
`f= muR`
`=mu mg`
Here maximum static friction (26.46 N) `gt ` force acting on block (7.5 N)
( b ) When obersever is moving with trolley .this will be non- inertia reference frame . Hence to observer block appear to be stationary.