1) What is friction? a) Force that resists the sliding or rolling of one solid object over another b) Force that resists the sliding rolling of one liquid object over another c) Force that resists the sliding or rolling of one gas object over another 2) When rolling friction occurs? a) Occurs when a animal, ball, or cylinder rolls freely over a surface. b) Occurs when a wheel, car, or cylinder rolls freely over a surface. c) Occurs when a wheel, ball, or cylinder rolls freely over a surface. 3) Why coefficient of sliding is greater than coefficient of rolling? a) Because fiction are generally 200 to 3,000 times greater b) Because fiction are generally 100 to 1,000 times greater c) Because fiction are generally 500 to 9,000 times greater 4) Surface in relative motion are called? a) Kinetic friction b) Static friction c) Force friction 5) The main source of friction in rolling appears when? a) Dissipation of energy involved in deformation of the objects b) Dissipation of the human involved in deformation of the objects c) Dissipation of the animals involved in deformation of the objects 6) The value of the coefficients of friction for a case of one or more bricks sliding? a) 1 b) 0.5 c) 1.5 d) 3 e) 2.7 f) 0.7 7) Two simple experimental facts characterize the friction of sliding solids ? a) First the amount of statistic b) First the amount of force c) First the amount of friction 8) Static friction, in contrast, act between? a) Surfaces at rest with no respect to each other b) Surfaces at rest with respect to each other 

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