Question

Please help and explain!!!

Traveling with the wind, Jerry takes 10 minutes to bike to the local library. Traveling against the wind, it takes him 15 minutes. The library is 2.5 km away. What is Jerry's bicycling speed in still air?

Answer 1

`0.2\ km\ per\ minute`

Explanation:

`As\ we\ are\ given\ that,\\Time\ Jerry\ takes\ with\ the\ Force\ of\ Wind\ in\ his\ direction=10\ minutes\\Time\ Jerry\ takes\ with\ the\ Force\ of\ Wind\ against\ his\ direction=15\ minutes\\Considering\ only\ the\ direction\ of\ the\ forces\ are\ opposite\ and\ the\\ magnitudes\ equal,\\Let\ the\ time\ Jerry\ take\ travelling\ through\ a\ still\ wind\ be\ x\\Let\ the\ Force\ of\ wind\ be\ F.\\Hence,\\x+F=10\\x+(-F)=15\\By\ simply\ adding\ the\ equations,\\2x=10+15\\2x=25\\x=(25)/(2)\\`

`x=12.5\\Hence,\\Time\ taken\ by\ Jerry\ during\ a\ still\ wind=12.5\ seconds.\\We\ also\ observe\ that\ 12.5\ is\ the\ mean\ of\ 10\ and\ 15\ and\ lies\ between\\ the\ two\ extremes.\\Hence,\\As\ we\ now\ know\ that,\\Distance\ from\ the\ library=2.5\ km\\Time\ taken\ by\ Jerry\ during\ the\ still\ wind=12.5\ minutes\\Hence,\ we\ know\ that\\Speed=(Distance)/(Time)\\Here,\\Speed=(2.5)/(12.5)\\Speed=(1)/(5)\ or\ 0.2\ km\ per\ minute`