Answer:
Explanation:
Your question is quite confusing, particularly the information about microsecond = 0.5.
I'm going to ASSUME that you mean coefficient of static friction μs = 0.5
unfortunately typing a subscript "s" is very difficult and probably leads to such confusion.
I will also ASSUME that the block, and spring, and force vector are all horizontal.
If the force is slowly increased until the block slips, the spring will compress until the force on each end equals the maximum static friction force. As we are not concerned with the compression distance, only the force, we can ignore the spring constant information and simply find the maximum available static friction force.
F = μN
F = μmg
F = 0.5(4.0)(9.8)
F = 19.6 N
Not that it matters, but the spring will have extended or compressed 19.6/0.8 = 24.5 m, which is a very long and very light spring
