単位と物理量 https://hirakawatblog.com/%e7%89%a9%e7%90%86%e5%9f%ba%e7%a4%8e%e3%80%81%e7%89%a9%e7%90%86%e3%81%8c%e8%8b%a6%e6%89%8b%e3%81%aa%e7%94%9f%e5%be%92%e3%81%b8/%e5%8d%98%e4%bd%8d%e3%81%a8%e7%89%a9%e7%90%86%e9%87%8f