CALC A balky cow is leaving the barn as you try harder and harder to push her back in. In coordinates with the origin at the barn door, the cow walks from $x=0$ to $x=6.9 \mathrm{m}$ as you apply a
force with $x$ -component $F_{x}=-[20.0 \mathrm{N}+(3.0 \mathrm{N} / \mathrm{m}) x] .$ How
much work does the force you apply do on the cow during this displacement?