4. A 6 m long 20 kg ladder leans against a frictionless wall at an angle of 60°. What is the minimum coefficient of friction between the ladder and the floor? a) 0.26 b) 0.27 c) 0.28 0.29 e)0.30 5. A 6 m long 50 kg ladder leaning on a frictionless wall can successfully be scaled by a 150 kg man. The coefficient of friction with the floor is 0.5. What is the minimum angle between the ladder and the floor? a) 55° b) 60 6 d) 70° e) 75°