physics
posted by sam .
The velocity of a ball changes from ‹ 8, −5, 0 › m/s to ‹ 7.88, −5.28, 0 › m/s in 0.04 s, due to the gravitational attraction of the Earth and to air resistance. The mass of the ball is 140 grams.
I calculated the acceleration and got <3,7,0>
what is the equation to find the rate of change of momentum of the ball?

Force = rate of change of momentum = m a if mass is constant
(7.88  8)/.04 = 3
(5.28+5) /.04 = 7
(0  0 ) = 0
so yes
m a = .140 (do it in kg) * that a vector 
By the way, Newton 2 is
force = rate of change of momentum
F = m A is the simple version but will not work if mass is not constant (rocket or special relativity for example)