Tractor friction work

A tractor pulls a tree trunk weighing 1.5 t for a distance of 2 km along a horizontal road at a constant speed. What mechanical work does it do if the coefficient of sliding friction is 0.6?

Final Answer:

W =  18 MJ

Step-by-step explanation:

$$\begin{gathered} m=1.5\text{t}\to \text{kg}=1.5\cdot 1000\text{kg}=1500\text{kg} \\ s=2\text{km}\to \text{m}=2\cdot 1000\text{m}=2000\text{m} \\ k=0.6 \\ g=10{\text{m/s}}^2 \\ G=m\cdot g=1500\cdot 10=15000\text{N} \\ F=k\cdot G=0.6\cdot 15000=9000\text{N} \\ {W}_1=F\cdot s=9000\cdot 2000=18000000\text{J} \\ W=W_1/10^6=18000000/10^6=18\text{MJ} \end{gathered}$$

Try another example