posted by sam on .
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
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)