I read in my textbook that an object can have constant velocity when net force and acceleration are equal to 0. For an example like a puck on frictionless ice that continues to move after it has had a force applied to it that is all good and fine, I understand that inertia keeps the puck moving. I am wondering how in an example similar to the above, the object can have constant velocity and net force can be equal to 0, with horizontally applied forces that are NOT equal to 0. For example, a puck being pushed by a hockey stick on some snowy ice, or me pushing a book across a table. Doesn't the applied force from the hockey stick or the force from my hand have to be greater than the force of friction from the ice or the table for the puck or book to move? if this is true, then net force is not equal to 0, yet the puck/book still has constant velocity and now all of Newton's principles make no sense to me. I'm hoping someone can clarify this/these concept(s). Thanks! EDIT: I'll add one more question here, how would you calculate (not specifically, just conceptually) the acceleration of an object that has constant speed but changing direction only?