A Wooden Block Slides Directly Down an Inclined Plane, at a Constant

Multiple Choice

A wooden block slides directly down an inclined plane, at a constant velocity of 6.0 m/s. How large is the coefficient of kinetic friction, ?_k, if the plane makes an angle of 25.° with the horizontal?

A) 1.2
B) 0.37
C) 0.42
D) 0.91
E) 0.47