Difference Between Contact and Non-contact Forces

Contact vs Non-contact Forces

Forces are a phenomena or a concept that is used to describe mechanical activity in physics and mathematics. The idea of a force is very important in fields such as mechanics, astronomy, physics, mathematics, statics and various other fields. Contact forces and non-contact forces are two ways the forces can be categorized. Both of these forces are common in nature and are vital in understanding the natural system. In this article, we are going to discuss what forces are, what contact forces and non-contact forces are, their definitions, the similarities between contact forces and non-contact forces, under what circumstances contact forces and non-contact forces occur and finally the difference between contact forces and non-contact forces.

What are Contact Forces?

To understand what contact forces are, one must first have a proper understanding in the concept of force. The common interpretation of force is the ability to do work. However, all forces do not do work. Some forces merely attempt to do work. And there are other causes for work apart from force. Heat is also capable of doing work. The proper definition of force is “any influence that causes or attempt to cause a free body to undergo a change in the acceleration or the shape of the body.” Acceleration can be changed either by changing the velocity of the object or by changing the direction of the object or both.

Contact forces are forces that are exerted by contacting of two surfaces. For an example, the forces acting on each other when one object is kept on top of another are contact forces. In this case, contact forces arise to balance out gravity, a non-contact force. Contact forces also occur when two objects collide. Under collisions, the contact forces create impulses. Friction and viscosity are two good examples for contact forces. For contact forces, the effect of the force takes place immediately after the force is applied.

What are Non-contact Forces?

Non-contact forces are forces that do not require any physical connection between the two objects involved. Non-contact forces can also be represented in vector fields. Gravitational force, magnetic force, electric forces are some examples for non-contact forces. Since non-contact forces are forces acting on a distance, there is a time gap between a cause and an effect. For an example, if an electromagnet is stopped, the objects attracted to the magnet at a distance will feel a very small time lag. The lag experienced is equal to the time taken for light to reach the point from the object. If the sun vanishes from where it is now, the earth would feel the effect only after 8 minutes (time taken for sun light to come to the surface of the earth).


What is the difference between Contact Forces and Non-contact Forces?

• Contact forces take effect immediately after the force is applied whereas there is a time gap between the application and the effect of non-contact forces.

• Contact forces can be represented by vectors. Non-contact forces can be represented by vector fields.

• There is always a field associated with a non-contact force, but there are no fields associated with a non-contact force.


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