“An object in motion tends to remain in motion along a straight line unless acted upon by an outside force.”
- January 4, 1643 – March 31, 1727
- Born in England (UK)
- Natural philosopher, mathematician, physicist, astronomer, theologian
- Proposed the laws of universal gravitation and motion, built the foundations of modern science, and systematized theories of natural philosophy and mathematics.
Quote
“An object in motion tends to remain in motion along a straight line unless acted upon by an outside force.”
Explanation
This quote represents Newton’s First Law of Motion, often referred to as the law of inertia. Newton is stating that an object will continue in its current state of motion (either at rest or moving in a straight line at constant speed) unless it is acted upon by an external force. In other words, the object will not change its state of motion on its own; something must influence it for any change to occur. This law was revolutionary because it fundamentally changed the way people understood motion. Prior to Newton, the dominant idea (inherited from Aristotle) was that objects required a continuous application of force to keep moving. Newton’s insight, based on his work with gravity and mathematics, showed that objects naturally tend to maintain their motion unless forces, such as friction or gravity, interfere.
The law of inertia provides the foundation for much of classical mechanics, influencing not only how we understand objects on Earth but also how we comprehend motion in space. For example, in the absence of friction or other external forces, a spacecraft in space would continue in a straight line at a constant speed indefinitely, as there is no force acting to change its velocity or direction. Similarly, this principle is applied in everyday scenarios, such as when a car suddenly stops, and the passengers feel a jolt forward because their bodies want to continue moving at the car’s original speed (due to inertia).
In modern physics, Newton’s First Law remains essential for understanding the motion of objects, especially in contexts like space travel, engineering, and astronomy. It was a key component in the development of Newtonian mechanics and continues to inform how we calculate and predict the behavior of objects in both everyday situations and in more extreme conditions.
