Pls explain the following

f=v dm/dt
=v(_av)
=_av^2

what is the 2nd v in the bracket? ? where does it come from? ?

How are momentum and impulse related? impulse is a whim to do something, while momentum keeps it going impulse is another name fore instantaneous momentum the impulse acting on and object is equal to the change of momentum it causes. the impulse that acts on and object is the momentum that results.

Automobile fuel efficiency is often measured in miles that the car can be driven per gallon of fuel (mpg). heavier cars tend to have lower fuel efficiencies (lower mpg ratings). which variable (weight or fuel efficiency) is most naturally considered the explanatory (predictor) variable in this context?

It takes a lot of energy to get the temperature of water to increase and eventually boil because water has a high heat.