The coefficient of static friction is 0.693 between the two blocks shown. The coefficient of kinetic friction between the lower block and the floor is 0.110. Force F causes both blocks to cross a distance of 4.55m, starting from rest. What is the least amount of time in which the motion can be completed without the top block sliding on the lower block, if the mass of the lower block is 1.45kg and the mass of the upper block is 2.29kg?

Question

***[isuru]*** · Answer

hi, 
   First it would be easy if you figure out the forces acting here
|dw:1379873604362:dw|

R1 - reaction due to 2 masses
F1 - friction between floor and 2 blocks
F2 - friction between upper block and lower block