There is now a new article called How Time Works that answers all of these questions about clocks and calendars, plus many more! You will be amazed, because we take all of this stuff completely for granted and the origins are amazing!
It's all fun and games when you're on a deserted island. But then the smoke monster shows up, a strange tribe kidnaps some of your fellow survivors and you realize you haven't had a drink of water in a long time. How bad can glugging seawater be?
How many regular-sized helium-filled balloons would it take to lift someone? What is the equation to figure it out?