A train starting from rest is moving along a straight track with a constant acceleration fo `2.5m//s^(2)`. A passenger at rest in the train observes a particle of mass 2kg to be at rest on the floor with which it has a coefficient of friction `mu_(s) = mu_(k) = 0.5` .Six seconds after the starting of the train , a horizontal force F = 13N is applied to the particle for two seconds duration. The passenger now observes the particle to move perpendicular to the direction of the train.
(a) calculate the kinetic energy of the particle with respect to the passenger at the end of 8 seconds after starting of the train.
( b) repeat the calculate of ( a) for an observer on the ground.

Answer

(a) 4J, ( b) 404 J