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? ?

According to newton’s law of universal gravitation, which statements are true? as we move to higher altitudes, the force of gravity on us decreases. as we move to higher altitudes, the force of gravity on us increases. as we gain mass, the force of gravity on us decreases. as we gain mass, the force of gravity on us increases. as we move faster, the force of gravity on us increases.