Motion and Its Causes

Force and Newton’s Laws of Motion

What are Newton’s Laws of Motion?

You have just explored how force and mass affect acceleration. Sir Isaac Newton (1642–1727) summarized these results in what is called Newton’s Second Law of Motion. For a single force, like you used, it can be written as: Acceleration is equal to the force applied divided by the mass, or a = F/m.

That is, the acceleration (a) varies directly with the force applied (F). The stronger the force, the greater the acceleration. And it varies inversely with the mass (m). The larger the mass, the smaller the acceleration.

What happens in there is no force? The equation says that there is no acceleration. That is, if the velocity was zero it remains zero. If the object was moving, it continues to move with the same velocity. These statements are called Newton’s First Law of Motion.


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