# Having problem with centripetal and centrifugal force

• Shafia Zahin
In summary, the centrifugal force is a fictitious force that is used when viewing things from an accelerated frame of reference. It is added to "fix" things so that Newton's 2nd law can be used.
Shafia Zahin
Hi,I was reading about the centripetal and centrifugal forces then I felt a bit of contradiction in the explanations. It is said that the centripetal and centrifugal forces are the action-reaction pair of Newton's 3rd law and so they never act upon the same body.Centripetal force is acted upon the body that is rotating in a circular path and the centrifugal force is acted upon the centre of the circular path.But we can see the effect of the centrifugal force not the centripetal force on the rotating body apparently. Because, it's the centrifugal force that tries to draw the body outwards the circle. Please make it clear.
Shafia.

Shafia Zahin said:
It is said that the centripetal and centrifugal forces are the action-reaction pair of Newton's 3rd law and so they never act upon the same body.
Be very careful here!

In typical physics usage, "centrifugal force" is a fictitious (or inertial) force that is only used when viewing things from an accelerated frame of reference. (Read about it here: https://en.wikipedia.org/wiki/Centrifugal_force)

In very atypical usages (in my opinion) some folks use a concept called "reactive centrifugal force", which is the definition that applies to what you read. (Read about that here: https://en.wikipedia.org/wiki/Reactive_centrifugal_force) To call that "centrifugal force" will confuse many physics folks. Don't do it!

So, imagine a ball tied to a string, whirled in a circle. Since there is a centripetal acceleration, there is a centripetal force: The force of the string pulling on the ball. No centrifugal forces involved since we are viewing things from an inertial frame of reference.

It's certainly true that the ball pulls back on the string, following Newton's third. No special name for that force is needed.

Viewed from a frame that rotates with the ball, the ball is not accelerating. (It's just sitting there.) To "fix" things so that Newton's 2nd law can be used, we add a fictitious outward centrifugal force that acts on the ball and "cancels" the inward centripetal force (a "real" force that exists in all frames). But unless you are studying non-inertial reference frames, I would skip it.

CWatters and Vibhor
Thank you.Now, I've become quite clearer in this topic.Hope that I'll be able to solve many problems in this regard more efficiently.

## 1. What is the difference between centripetal and centrifugal force?

Centripetal force refers to the force that keeps an object moving in a circular path towards the center. On the other hand, centrifugal force is the apparent outward force that an object experiences when moving in a circular path. It is not a real force, but rather a result of an object's inertia.

## 2. How do centripetal and centrifugal forces affect an object's motion?

Centripetal force causes an object to accelerate towards the center of a circular path, while centrifugal force acts in the opposite direction, pushing an object away from the center. These forces together are responsible for an object's circular motion.

## 3. What is the formula for calculating centripetal force?

The formula for calculating centripetal force is Fc = (mv^2)/r, where Fc is the centripetal force, m is the mass of the object, v is the velocity, and r is the radius of the circular path.

## 4. How does changing the radius of a circular path affect centripetal force?

As the radius of a circular path decreases, the centripetal force required to keep an object moving in that path increases. This is because a smaller radius means a tighter curve, which requires a greater force to maintain the object's circular motion.

## 5. Can centripetal and centrifugal forces be balanced?

Yes, centripetal and centrifugal forces can be balanced if the object is moving in a stable circular path. In this case, the centripetal force provided by a physical force, such as tension or gravity, is equal and opposite to the centrifugal force caused by the object's inertia.

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