The key difference between contact force and field force is that contact force is the normal or frictional force acting on a contacting surface, whereas field force is a vector field that acts upon a certain area of space.
Contact forces are responsible for most of the visible interactions that happen between macroscopic collections of matter. Field force or force field is a vector field that describes a non-contact force that acts on a particle at various positions in space.
CONTENTS
1. Overview and Key Difference
2. What is Contact Force
3. What is Field Force
4. Contact Force vs Field Force in Tabular Form
5. Summary – Contact Force vs Field Force
Contact force is a type of force that requires contact to occur. This type of force is responsible for most of the visible interactions that happen between macroscopic collections of matter. For example, pushing a car up a hill is an everyday application of contact force. Here, the continuous force applied by the person who is pushing the car is the contact force. Moreover, kicking a ball across a room is another example where the contact force is delivered in a short impulse. Often, contact force decomposes into orthogonal components, which are perpendicular and parallel components known as normal force and friction force, respectively.
Figure 01: Normal and Friction Forces on a Block
The normal force is created as a result of the Pauli exclusion principle. According to this principle, objects do not actually touch each other, and the contact force is created due to the interactions of the electrons at or near the surfaces of the objects. The atoms at these surfaces do not penetrate one another if there is not enough energy for this. In other words, the two objects in contact do not penetrate each other due to the stability of the matter.
Friction force is created due to both microscopic adhesion and chemical bond formation, which occurs due to the electromagnetic force. In addition, this force can be created due to the microscopic structures stressing into each other.
What is Field Force?
Field force or force field is a vector field that describes a non-contact force that acts on a particle at various positions in space. For example, the gravity of gravitational force is a type of field force created as a result of the attraction between two objects. This force models this attraction as a force of a massive body extended into the space around itself. In other words, this type of force is the map of the force that is felt over a particular area of space.
Figure 02: Area of Field Force
Some common examples of field forces include magnetic fields, electric fields, and gravitational fields. These forces can be defined as ways of showing a force felt over an area of space. For example, if we hold a compass near a magnetic field, its needle can move according to the magnetic field dimensions. The movement of the needle stops if we go away from the area that is affected by the magnetic field.
Contact force and field force are types of forces that we can observe around us. The key difference between contact force and field force is that contact force is the normal or frictional force acting on a contacting surface whereas field force is a vector field that acts upon a certain area of space.
The following table summarizes the difference between contact force and field force.
Summary – Contact Force vs Field Force
Contact force is a type of force that requires contact to occur, while field force or force field is a vector field that describes a non-contact force that acts on a particle at various positions in space. The key difference between contact force and field force is that contact force is the normal or frictional force acting on a contacting surface, whereas field force is a vector field that acts upon a certain area of space.
Reference:
1. “What Is Force? Contact Force – Frictional, Applied & Normal Force.” BYJUS, BYJU’S, 4 Aug. 2020.
Image Courtesy:
1. “Free body diagram2” By Krishnavedala – Own work (CC0) via Commons Wikimedia
2. “GravityPotential” By AllenMcC. – Own work This diagram was created with Mathematica. (CC BY-SA 3.0) via Commons Wikimedia
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