nando 1. What will happen to the coefficient of static friction between two objects if (a) the normal force between the objects is doubled? (b) the surfaces are lubricated with grease? 2. A 40.-N object requires 5.0 N to start moving over a horizontal surface. What is the coefficient of static friction? 3. Once the object of the last question is moving how much force will be needed to keep it moving: more than 5 N. less than 5 N. or exactly 5 N? Explain. 4. A 50. N horizontal force is needed to keep an object weighing 500 N moving at a constant velocity of 2.0 m/s east across a horizontal surface. What is the magnitude and direction of the frictional force acting on the object? 5. The coefficient of kinetic friction between a 780. N crate and a level warehouse floor is 0.200. Calculate the magnitude of the horizontal force required to move the crate across the floor at constant speed. 6. If a 30-N force is required to accelerate a 2-kg object at 10 m/s' over a level floor, then what is the magnitude of the frictional force acting on the object