What is a Centripetal Force?

Centripetal force may be called the force which is responsible for keeping a body or an object right in a circular path. This force always acts towards the centre of the path in which it is moving. In this type of force, no displacement of the object takes place due to an inward force.

For example, if a string tied to a stone is whirled, it exhibits centripetal force. This is because when it moves in a circular path, the force that acts over the stone is applicable inwards to the centre of the moving path. In other words, it can also be said that the object or the body is also known to be moving in a curvilinear motion towards the centre of curvature. 

What is the unit of centripetal force? 

Centripetal force is always calculated in Newton(N). Let us take the example of the moving stone again that has been mentioned before. While the stone is moving in a circular motion, the centripetal force that is acting right on the moving object is acting perpendicular to the direction in which the displacement of the object has taken place. One can find the centripetal force acting on a body using Newton’s second law of motion. With the help of Newton’s second law of motion, it is found that the direction of the moving object or body acts in an inward direction of the circular motion. 

How to calculate centripetal force? 

As is seen above, the centripetal force can be calculated with the help of Newton’s second law of motion, which states that the acceleration by which an object moves is produced by a net force that is directly proportional to the magnitude of the ultimate net force. And this acts in the same direction as the net force and is inversely proportional to the object’s mass. 

Now, the formula with which the centripetal force is calculated is-

Fc = mv2/r

Here F or Fc is the centripetal force that is acting on the object, m is the mass, v is the velocity, and r is the radius of the object. As is seen, the centripetal force is the resulting product of the mass (measured in kg) and the square of the velocity (measured in metres). And this product result is divisible by the radius (measured in metres). This means that the centripetal force is likely to be quadrupled on the doubling of the velocity. 

What is the difference between centripetal force and centrifugal force? 

Most of the time, people get confused between a centripetal force and centrifugal force. Let us see what the differences between centripetal force and centrifugal force are:

Centripetal force-

• A centripetal force always acts inwards to the centre of the circular path in which the body or the object is moving. It follows the second law of Newton, which states that the object which and when will move in a circular direction is meant to gain acceleration, thereby facing inwards or towards the centre of curvature, due to an inward force. 
• A centripetal force acting on a body is observed from the inertial reference frame. 

One example: when a car is moving in a circular direction, the centripetal force that is produced by the friction acting between the tyres of the car and the road surface is helping the car to move on the road in a circular direction. 

Centrifugal force-

• Centrifugal force is also known as pseudo force. Although it is a movement taking place in a circular motion, it will act along the radius but is directed away from the object; that is, it acts in an outward motion. The centrifugal force follows the third law of Newton, which states that every object has an equal and opposite reaction. A centrifugal force always acts outwards. The motion faces an outward direction from the centre of curvature. 
• A centrifugal force is always observed from the reference of a non-inertial frame. 

One example: Take the example of a car that is moving in a circular motion, and it is carrying passengers inside it. When the car is taking a right turn, the passengers inside the car will experience a slight outward force. The passengers will experience this because of the centrifugal force which has been acting upon them. 

Practical explanations and examples of centripetal force:

We experience the applications of centripetal force in our daily lives and even make use of it. It would help to see a few examples from our day to day activities to better comprehend what centripetal force means- 

1. Planets moving in a circular path: Earth moves in a circular orbit around the Sun. It is the centripetal force (along with the gravitational force of the Sun and other heavenly bodies) that keeps it in the circular path instead of having it drift off.
2. Car in a circular motion: Centripetal force keeps a car in a circular path when it is making a turn. If not for centripetal force (and friction), the force of inertia and centrifugal force would make it drift away.

Conclusion

Centripetal force refers to the force that acts on an object that is moving in a circular path in an inward direction of the path due to an inward force. The term has been taken from Latin, where centrum means centre and petere means to seek. It can be called a force that follows a curved path and acts orthogonally to the motion of the body in an inward direction of the centre of curvature of the circular path. One of the most important uses of the centripetal force is that because of the centripetal force, planets move in a circular motion in their orbits.