《AP Calculus》A plane flies horizontally at an altitude....Find the rate of the plan travels at some time
Question:
A plane flies horizontally at an altitude of 5 km and passes directly over a tracking telescope on the ground. When the angle of elevation is π/3, this angle is decreasing at a rate of π/6 rad/min. How fast is the plane traveling at that time?
單位換算一直是學物理化學中很多人的痛 比如莫耳濃度(Molarity, M)的分母體積單位要用公升(Litter, L),但是密度卻用公克除以立方公分,然而這些單位換算中,相信對同學最困擾的莫過去這個 “ppm, part per million”。 到底這個 ppm 要怎麼換算才會快呢?這邊我來分享個小訣竅,首先我們要先瞭解 ppm 的定義是什麼根據 wiki 上說的 part per million 定義為百萬分之一,意思是1ppm就是一百萬分之一。