Aweather balloon is inflated to a volume of 27.2 l at a pressure of 753 mmhg and a temperature of 30.9 ∘c. the balloon rises in the atmosphere to an altitude where the pressure is 395 mmhg and the temperature is -15.9 ∘c. assuming the balloon can freely expand, calculate the volume of the balloon at this altitude.

20) what is a magnetic field? 21) in which direction do magnetic field lines always point? 22) sketch a diagram showing how a plotting compass points around a 23) name two magnetic poles that will: a) attract each other b) repel each other. 24) explain why you can use a compass to navigate. 25) what's an electromagnet? 26) list two ways to increase the strength of an electromagnet. 27) the wire in a simple motor feels a force when a current flows through it. why is this? i need answers to check mine