How much force is required to push a 54-pound sofa across a carpeted floor?

Sounds like a problem from Physics.  The force required to push a 54 lb sofa across a carpeted floor is most likely LESS than 54 lb.  It depends upon the amount of friction between the bottoms of the sofa legs and the carpet.  In a typical Physics problem, you'd be given the "coefficient of dynamic friction" to assist your determination of how much force is required to push the sofa across the carpet.

Definitely