Physics is a highly esteemed branch of science that deals with the laws of nature. Nature shows certain strict laws that govern the movement of objects and planets. One such law is the law of force. The Law of force in physics means the push or pull acting on an object that affects the object’s motion.
While studying gravitational force, Sir Isaac Newton observed that certain force acts on objects that leads to the interaction of the two objects.
The idea stemmed from every planet’s gravitational field that causes attraction and pulls nearby objects towards itself. In contrast, the other planet’s gravitational field pulls it away. This causes orbital movements. In linear terms, Newton derived that the total amount of force acting on an object is the product of mass and acceleration.
Mass is the mass of the body causing push or pull. In this article, we will deal with the Comparison of Contact and Non-Contact Force and everything you should know about them.
Contact force, by its nature, is the force acting on bodies that are in direct contact. This we can derive by the name itself. A good example of a contact force would be pushing or pulling Hione object towards another.
So, if you push your car towards a wall, you are applying a contact force. Similarly, pulling your car towards yourself is also a contact force because there is direct contact between you and the car.
Now, non-contact force exhibits a completely different nature to those above. Non-contact force, by its name, is the force acting on two bodies that are not in direct contact.
An excellent example of a non-contact force would be when objects move without direct application of a force. So, if an apple falls from the tree, it is due to the gravitational force, which is a prime example of non-contact forces.
We looked at the basic traits of contact force above. However, we must look at this force more sophisticatedly to prove its applicability in physics. Sir Isaac Newton observed that when we apply a certain force to a body with a mass ‘m’, the body starts accelerating in the direction to which the force is applied.
This acceleration is represented with ‘a’. Considering the nature of contact force and the variables declared above, the final equation that comes out is the product of ‘m’ and ‘a’. Thus, the final equation is F=ma.
However, the effect of force application is not limited to change in acceleration. We must also remember that when an external force is applied, the body also changes momentum. The change in momentum is represented by ‘p’. Now, the rate of change of momentum is equal to the force applied.
The rate of change of any unit is denoted by ‘Δ’ (delta in common parlance). Hence, the final equation we get is F= Δp/Δt. Here, the fraction denotes the change in momentum per unit of time. Remember, the unit for change in momentum per unit time is kg-m/s.
Let’s look at different types of contact forces. Given below is a comprehensive list of contact forces:
- Air resistance
- Surface tension
- Buoyancy force and upthrust
- Applied force
- Drag force
- Muscular force
- Normal force
This segment will discuss some examples of contact forces to give you a clear idea and solidify your concept.
1. Consider a situation where you kick a football, and it flies off in the air and returns to the ground to rest.
Here, you will notice that the first force that acts on the football is your kick. Your kick throws the ball in the air and provides a certain projectile motion based on the direction in which you have kicked.
Once the ball is in the air, the air resistance and frictional force start acting on the ball. These forces slow down the ball, and eventually, the ball comes back to the ground and rests.
2. Let’s assume that you have spring to play around with. Now, if you stretch the spring, it will oscillate from its mean position. However, after a while, you will notice that the spring is regaining its original form.
The stretching of the spring is the first application of contact force. And the spring gets back to its original position by the restoring force.
3. Adventurous activities like bungee jumping, paragliding and skydiving are also good examples of contact forces.
In this segment, we will look at some examples of non-contact forces so you can find the distinction.
1. Our routine involves multiple applications of electricity via multiple devices. But, how does the electricity reach us? No one is throttling the electrons towards our homes. This happens because the wire that reaches our homes has millions of electrons.
All these electrons possess a random motion. Now, the flow of this motion is determined by an invisible force called the electric force.
2. Coulomb’s law and its governing principles stem from the nature of non-contact forces.
3. A basic project that we all make during an exhibition or a fair is making a magnet out of a wire and a nail. Now, we wrap the wire around the nail and supply electric current to it. This creates a magnetic field around the nail, and it starts attracting objects.
This happens because the millions of electrons possessing random motion get pointed in one direction when electricity is supplied.
In this article, we discussed the nature and principle of contact and non-contact forces. We also discussed some examples to give you a conceptual understanding of the subject.
Further, you can read more about non-contact forces online if your curriculum does not include them. Non-contact forces govern space and time around us. Similarly, contact forces are participants in our day to day activities. Both these forces have wide applications in several industries today.