What is a good reashrch question on water evaporating and salt staying

Which situation will produce the greatest change of momentum

What quantity do units represent in value

A15,000 kg rocket traveling at +230 m/s turns on its engines. over a 6.0 s period it burns 1,000 kg of fuel. an observer on the ground measures the velocity of the expelled gases to be −1,200 m/s.