# What is First Moment of Area?

In this article we will discuss about definition of first

moment of area or moment of area, application and example. We will also derive

the formula for it.

moment of area or moment of area, application and example. We will also derive

the formula for it.

## First Moment of Area

Considered a thick lamina or a body having area A. let x is

the distance of C.G. of the area from the axis OY and y is the distance of C.G.

of the area from the axis OX.

the distance of C.G. of the area from the axis OY and y is the distance of C.G.

of the area from the axis OX.

Here

x = Distance of C.G. of area A from axis OY

y = Distance of C.G. of area A from axis OX

Then,

This equation (1) is known as the first

moment of area about the axis OY

Similarly

This Equation (2) is called the first

moment of area about the axis OX.

moment of area about the axis OX.

### Conclusion:

#### First moment of area/moment of area:

The first moment of area of a lamina

about an axis is defined as the product of area of the lamina and the

perpendicular distance of the C.G. of the area form the axis.

about an axis is defined as the product of area of the lamina and the

perpendicular distance of the C.G. of the area form the axis.

### Application

It is used to determine the center of

gravity of area.

gravity of area.

### Numerical Example

If we have a lamina having

area 10 cm2 and the distance of its C.G from the axis are shown in

the figure given below.

area 10 cm2 and the distance of its C.G from the axis are shown in

the figure given below.

Then

The first moment of area about axis OY =

10 x 5 = 50

10 x 5 = 50

The first moment of area about axis OX =

10 x 7 = 70

10 x 7 = 70

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