How would you convince somebody that the momentum of an isolated system is constant?

check all that apply.
a. derive it from newton's second and third laws.

b. use it to make predictions about a experiment (for example, collision of two bodies), and then compare the outcome to the prediction.

c. use an example from a textbook to show that the sum of the initial and final velocities of the objects involved in a collision are the same.

d. it is a postulate; thus, you do not need to convince anybody.