Apply Work-Energy Theorem Practice Test

A $10,\text{kg}$ box slides $6.0,\text{m}$ to the right on a horizontal floor. A kinetic friction force of $25,\text{N}$ acts to the left, and a horizontal applied force of $40,\text{N}$ acts to the right. What is the net work done on the box over the $6.0,\text{m}$ displacement? (Include sign.)

A $2.0,\text{kg}$ cart on a level track has an initial speed of $12,\text{m/s}$. A constant friction force of $4.0,\text{N}$ acts opposite the motion until the cart stops. Using $W_{\text{net}}=\Delta KE$, how far does the cart travel before stopping (in m)?