Physics for IGCSE & O level - Forces And Motion (Section 13 - No. 19)
Which of the following best describes Newton's First Law of Motion?
For every action, there is an equal and opposite reaction.
An object at rest stays at rest, and an object in motion stays in motion with the same speed and in the same direction unless acted upon by an unbalanced force.
Force equals mass times acceleration.
Momentum is conserved.
Paliwanag
Newton's First Law is also known as the law of inertia.