# Force and Acceleration

From Newtonâ€™s II law of motion we know that F = ma. The acceleration produced in a body is directly proportional to the force acting on it and inversely proportional to its mass. Thus if mass is doubled, acceleration will be halved and if mass is halved, acceleration will be doubled, provided the force remains constant. Since the acceleration produced is inversely proportional to the mass of the body, it will be easier to move light bodies, than to move heavy bodies.ÂThe velocity of a moving object is the rate at which its position or location changes and is measured in units of length per time.

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**Example :** Metres per second or miles per hour.

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The acceleration of a moving object is the rate at which its velocity changes and is measured in units of length per time^{2}.

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**Example :** Miles per hour^{2} or meters per second^{2}.

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The mass of an object measures its resistance to acceleration or its inertia. In the metric system, mass is measured in units of grams or kilograms.

When a force is applied to an object it produces an acceleration which gives the ratio of applied force to its mass.

This equation is known as Newton's Second Law of Motion. Thus,

F = ma

and we see that force is measured in units of mass time length per time^{2} - for example, gram-metres per second^{2}.

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Two common units of force are Newton and dyne. One Newton is one kilogram-metre per second^{2} and one dyne is one gram-centimetre per second^{2}. Thus, one Newton is 10^{5} dynes.

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