According to the meaning of the question, the sliding friction force fmax = μ fn = μ g = 0.4×150n = 60n,

Therefore, the minimum thrust is 60N；;

According to the kinetic energy theorem, we can know that WF-Ffs=0-0,

Solution: WF=Ffs=60×0. 1J=6J.

So the answer is: 60; six