two mass connected by string on a slide... about the work and energy things

Question

There a mass of 4kg and a mass of 5kg connected by an inextensible string passing over a smooth pulley .the mass for 4kg starts from rest and moves up the smooth plane inclined at 30degree to horizontal ,what is the velocity of masses when the 4kg mass moves a distance of 2m along plane?? https://s.yimg.com/hd/answers/i/c348025790a34759a306b7828df9e0f5_A.jpeg?a=answers&mr=0&x=1447429634&s=3f339b4c3f9c2111ee62a181142ec178

Answer 1

f=m* ds for m1=4kg implies that 4*2=8 but for m2 ds is 0 therefore f is 0 then a=f/m=8/4=2m/s but a2=0 m/s v=adt=2*1=2m/s