Hey guys, I have a test tomorrow in physics and although I'm a good student, physics is getting tougher this year (high school 1st year for me) and our teacher is really bad, her teaching skills are very poor. Plus, I've been absent for a couple of days when we had physics and I can't solve the "hard" problems. The lesions these problems are related to are Power, Work and Kinetic Energy. 1) A cube is sliding on the floor for 4 meters, it changes it's speed from 1meters/second to 0,2 meters/s. Find the friction coefficient (no weight of cube given ???) 2) A cube is horizontally moving on a table, there are 4 forces on it, G, N and F1 and F2, F1 is on the right of the cube pulling it, F2 is pulling it from the left. F1=3F2. If during Δt, ΔEK of ONLY F1 is 3Ek, then ΔEk during this time of all of the forces is? a) 2Ek; b)Ek; c)0,75Ek; d) 0,25Ek Thanks a lot guys!