It takes a 50 N horizontal force to pull a 20 kg object along the ground at constant velocity. Therefore the coefcient of friction is . (Give your answer with the correct number of significant digits). AJ Question 2 (2 points) The frictional force that must be overcome to start a 50 kg object sliding across a horizontal surface when the static coefficient of friction is 0.35 is ___x102 N. (Give your answer with the correct number of significant digits and do not include units). ex Question 3 (2 points) The coefficient of static friction between a book and the level surface it slides on is 0.65. If the mass of the book is 2.0 kg, the minimum initial applied force required to slide the books across the surface is _N. (Give your answer with the correct number of significant digits and do not include units). t/ An engine provides 5.0 kN of force to keep a 1600-kg vehicle moving at a uniform speed. (Air resistance is negligible.) The coefficient of rolling friction between the tires and the road surface is _. (Give your answer with the correct number of significant digits). t/