What is the average speed of a bird that flies 1.55 km in 30 minutes

If you put a helium-filled balloon in the refrigerator, what will happen?

(a) if the pressure in gas is doubled while its volume is held constant, by what factor do (i) vrms and (ii) change? (b) is it possible to boil water at room temperature (20oc) without heating it? explain.

Galileos view of arrangement of the universe