Question

"when the net force is 0 the object moves with the constant velocity."how can the object even move with 0 net force?

Answer 1

Hi,

Here is your answer

We know that by Newton's first law of motion,"Every object contiues to be in the state of rest or state of motion unless an external unbalanced forced is applied on it"

Here, Given that the net force including friction is 0, ad the body was initially moving, there is no force acting upon it to either increase or decrease it's speed. As long as the friction remains 0 and no other forces act up on it, the body will move with a constant velocity.

Hope this helps you.