What is it called when earth’s magnetic poles change places?

2pos suppose an object in free fall is dropped from a building. its starting velocity is 0 m/s. ignoring the effects of air resistance, what is the speed (in m/s) of the object after falling 3 seconds? give your answer as a positive decimal without units. answer here

Adepositional also feature that forms where a stream enters a lake or an ocean is a

What mass of natural gas (ch4) must you burn to emit 276 kj of heat?