Which of the following is Newton's First Law of Motion, generally termed the Law of Inertia?
1) An object at rest tends to stay at rest and an object in motion tends to stay in motion with the same speed and in the same direction unless acted upon by an unbalanced force.
2) The acceleration of an object is directly proportional to the net force applied to it and inversely proportional to its mass.
3) For every action, there is an equal and opposite reaction.
4) None of the above