**Motion of Particles Under Gravity in Vacuum**

An object that **falls through a vacuum** is subjected to only one external force, the gravitational force, expressed as the weight of the object. The weight equation defines the weight **W** to be equal to the mass of the object **m** times the gravitational acceleration **g.**To know more about Motion of Particles Under Gravity in Vacuum,watch Motion of Particles Under Gravity in Vacuum Video to learn more .

W = m * g

The value of **g** is 9.8 meters per square second on the surface of the earth. The gravitational acceleration **g** decreases with the square of the distance from the center of the earth. But for many practical problems, we can assume this factor to be a constant. An object that moves because of the action of gravity alone is said to be **free falling**. If the object falls through the atmosphere, there is an additional drag force acting on the object and the physics involved with the motion of the object is more complex.

The motion of any moving object is described by Newton’s second law of motion, force **F** equals mass **m** times acceleration **a**:

F = m * a

We can do a little algebra and solve for the acceleration of the object in terms of the net external force and the mass of the object:

a = F / m

For a free falling object, the **net external force** is just the weight of the object:

F = W

Substituting into the second law equation gives:

a = W / m = (m * g) / m = g

The **acceleration** of the object equals the gravitational acceleration. The mass, size, and shape of the object are not a factor in describing the motion of the object.

Useful for CBSE, ICSE, NCERT & International Students

Grade :9

Subject : Physics

Lesson : Gravitation

Topic:Motion of Particles Under Gravity in Vacuum Video

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