Astronomy Fundamentals

Medieval Andrenaissance Astronomy

What is Newton’s First Law of Motion?

According to Newton’s First Law, “Every body continues in its state of rest, or of uniform motion in a right line, unless it is compelled to change that state by forces impressed upon it.” This is also known as the law of inertia: it simply means that an object tends to stay still, or stay in motion in a straight line, unless it is pushed or pulled. This law is an expression in words of a fundamental property of motion called the conservation of linear momentum. Mathematically, the momentum of an object is its mass multiplied by its velocity.


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