Second one: Kelvin is a measurement of temperature. Its symbol is K. I don't get the third one. Pascal is how you measure pressure, and 1 pascal equals 1 Newton/1 square meter. Mew (mu) is the coefficient of friction. You need friction to stay on a sloped roof. And the last one is a joke that is also a rhetorical question. The question is the answer.
The irony.
1024 mb = 1 gb