than to keep it moving. What best explains this observation?A. The mass of the sofa is greater than the mass of the carpet over it.B. The coefficient of static friction is less than the coefficient of kinetic friction.C. The sofa weighs less when it is moving.D. The coefficient of static friction is greater than the coefficient of kinetic friction.E. Force is directly proportional to acceleration.
D. The coefficient of static friction is greater than the coefficient of kinetic friction. Explanation: Force needed to start moving the sofa is: F? = k? * N, where F? is applied force, N is normal force (equal in intensity to weight of sofa, if the surface is horizontal) and k? is coefficient of static friction. Once the sofa is on the move, coefficient of dynamic friction is what determines the force necessary to continue moving the sofa: F? = k? * N, where F? is applied force, N is normal force (equal in intensity to weight of sofa, if the surface is horizontal), and k? is coefficient of dynamic friction. Since the question states that F? F?, it follows that k? k?.
