We have started a new topic in our previous post i.e. engineering mechanics. We have seen thereÂ the basics of engineering mechanics such asÂ concept of force system,Â principle of transmissibility of forcesÂ and its limitations, classification of force systemÂ and composition and resolution of forces in mechanics.Â

Now, we will be interested to understand here the body force and surface force in mechanics with the help of this post.Â

### Body force and surface forceÂ

As we have already seen that forces are acting between two bodies those are directly interacted with each other or might be at a distance away and not interacted directly.Â

Therefore, we can classify the forces in two types on the basis of interaction between two bodies and these are as mentioned here.Â
1. Body forces
2. Surface forcesÂ

### Let us first understand the body forcesÂ

Body forces act on each volume element of the body and these are exerted when the body will be kept in a gravitational, centrifugal, electric or magnetic field.Â

The best example of body force is the force due to gravitation and which is usually known as weight of the body.Â

Let us consider the example of apple falling down from its tree due to force of gravitation.Â Â

Gravitational force i.e. force of the earth on the body or object (here apple in the example) will be one good example of body force.Â

Briefly, we can say that body forces are the forces acting on the volume of the body.Â

### Example of body forcesÂ

Following are few examples for body forces which will help us to understand the basics of body forces.Â
1. Gravitational forceÂ
2. Centrifugal forceÂ
3. Electric fieldÂ
4. Magnetic FieldÂ
5. Inertia forceÂ

### Surface forces

Surface forces act on each surface element of the body and these are exerted when the body will be kept in direct mechanical contact with another body.Â

The best example of surface force is the pressure force, viscus force etc.Â

Briefly, we can say that surface forces are the forces acting on the surface of the body.Â

Let us consider the following figure where a person is pulling a load, such force will be one example for surface force as there is direct mechanical contact between two bodies.Â

### Example of body forcesÂ

Following are few examples for surface forces which will help us to understand the basics of surface forces.Â
1. Pressure forceÂ
2. Viscus forceÂ
3. Frictional forceÂ
4. Normal forceÂ

Therefore, we have seen here theÂ basics of body force and surface force with the help of this post.Â Â

DoÂ you have any suggestions? Please write in comment box and also drop your email id in the given mail box which is given at right hand side of page for further and continuous update fromÂ www.hkdivedi.com.Â

Further we will find out, in our next post,Â moment of force in engineering mechanics.Â Â

### Reference:Â Â

Engineering Mechanics, By Prof K. RameshÂ