Physics

Problem

4.0\,\text{kg}

box slides to the right on a horizontal surface while a constant

12\,\text{N}

force pulls it toward +x. The coefficient of kinetic friction varies with time according to

\mu_k(t)=0.10+0.020\,t

, where

t

is in seconds. Take

g=9.8\,\text{m/s}^2

. At what time will the box first begin to slow down? a)

5.1\,\text{s}

15\,\text{s}

10\,\text{s}

8.2\,\text{s}