試題詳解

31. An object of mass m is sliding with speed v at some instant across a level tabletop, with which its coefficient of kinetic friction is µ. It then moves through a distance d and comes to rest. Which of the following equations for the speed v is reasonable? (Gravitational acceleration is g)
(A) (2μgd) ^1/2
(B) (mgd) ^1/2
(C) (2μmgd) ^1/2
(D) (2μgd) -^1/2
(E) (2μd) ^1/2