A ball of mass 2.0 kg moves with a velocity of 4.0 m/s. A force of - 6.0 N is applied for 3.0 sec. Find the final velocity.

M = 2kg, u = 4 m/s, F = - 6 N, t = 3 s

From Newton's second law of motion,

F = m * a

= m * (v-u) / t

Therefore,

-6 = 2 * (v-4) / 3

(v-4) = - 9

v = - 5 m/s

(Note : The negative velocity indicates that the ball has a net velocity in the direction opposite of it's initial motion, i. e it is stopping)