If the velocity of an object is changing, its momentum is also changing.
true or false

It is absolutely true that when the velocity of an object changes, the momentum of the object also change. Momentum of any object is defined as the multiple of velocity of an object and the mass of the object. So we can easily deduce that momentum is directly proportional to velocity of an object if the mass of the object remains constant. So it can be seen that if the mass of the object does not change then any change in velocity is bound to have an effect on the momentum of the object. We can easily write the equation as momentum= mass x velocity.

Newton's first law describes something special that results from the sum of all the external forces (including gravity) on an object.