A box of unknown mass is sliding with an initial speed

vi = 5.10 m/s
across a horizontal frictionless warehouse floor when it encounters a rough section of flooring
d = 4.20 m
long. The coefficient of kinetic friction between the rough section of flooring and the box is 0.100. Using energy considerations, determine the final speed of the box after sliding across the rough section of flooring.

2 answers

Vf^2=Vi^2+ 2 ad
where a= force/mass=mg*mu/m=mu*g
solve for Vf
Vf^2=Vi^2+ 2 ad
where a= force/mass=mg*mu/m=mu*g
solve for Vf. acceleration is NEGATIVE, of course.