Toboggan run

The length of the toboggan run is 60 m, and the height is 8 m. The boy pulls a sled weighing 15 kg. How hard does the boy pull the sled uphill?

Correct answer:

F =  20 N

Step-by-step explanation:

$$\begin{gathered} s=60\text{m} \\ h=8\text{m} \\ m=15\text{kg} \\ g=10{\text{kg/m/s}}^2 \\ \sin \alpha =h:s=h/s \\ \alpha =\frac{180°}{\pi }\cdot \arcsin (h/s)=\frac{180°}{\pi }\cdot \arcsin (8/60)\doteq 7.6623{}^{\circ } \\ G=m\cdot g=15\cdot 10=150\text{N} \\ F=G\cdot \sin (\alpha ) \\ F=G\cdot h/s=150\cdot 8/60=20\text{N} \end{gathered}$$

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