\f5. The co-efficient of kinetic friction between a 20kg box and a floor is0.40. How much work does a pulling force do on the box in pulling it 0.8m across the floor at constant speed. The pulling directed 370 above the horizontal.1'. A roller coaster car with mass 641]]:3 moves along the track shown in below gureta] [f the roller coaster starts from rest at point A ,what is the total mechanical energy at point A. {b}What is the total mechanical energy at point B {CJCalctIlate the total speed of the roller coaster when it is reaches point B and C {d} If the car starts with a speed of llmls at point A, calculate the speed of the roller coaster when it reaches points B and C. \f(d) Answer the following question. After 10 years, a 10mg sample of argon-42 has decayed to 81mg.Estimate the half life of argon-42 11.Determine the energy yield of the following fission reaction. Use the given masses below 235 92U + on=TH +40Zr+ $2 Te + 3in where mzy-94 = 93.906u, mTe-139 = 138.935u