Tis' the season
Entry posted by ZZ
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Greetings Comrades,
Fall has many seasonal activities that come with it. One of these that I find rather unpleasant is raking/blowing leaves, due to its apparent futile nature. This past weekend, since my dad purchased another leaf blower, we were both able to use one and cut the time in half nearly to do our house's leaves. However, using a leaf blower can be frustrating due to the forces of air resistance and wind, which take away a substantial amount of kinetic energy from the leaves.
Even the highest power of leaf blowers only blow at speeds of 120m/s. So theoretically, if the leaf were in the air for 1 second, the leaf should go 120m (neglecting air resistance). In this instance, air resistance causes the leaf to only go maybe 12m. Not only is it frustrating to see more leaves falling where you just cleaned up, but the fact that the leaves only go a short distance makes it even worse.
Part of the reason the leaf experiences so much resistance is due to its surface area. Air resistance is largely determined by the amount of air molecules an object collides with in its intended path of travel. For example, if you took a marble and a leaf (of equal mass) and dropped them from a height of 20m, the marble would hit the ground first every time. Why is this? After doing some intense research, I believe it's because the leaf is making more "collisions" with the air molecules which slow it down more than the marble. It would take more of these collisions for the marble to reach its terminal velocity due to a lower area of contact, whereas the leaf reaches its fairly quickly. Th leaf's shape essentially causes it to be displaced less by the impulse from the leaf blower.
Looks like I'll have more time to ponder such thoughts in the future, as my lawn is coated in leaves currently.
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