Question

With reference to the direction of action, how does a centripetal force differ from centrifugal force?
A. They act in opposite direction
B. They act as action reaction pair
C. They act in same direction
D. Both A and B

Answer 1

Hint: Centripetal force and centrifugal forces act on a circular motion of an object or body. The both forces do not follow Newton’s third law of motion of action reaction pair, as they act on the same object. Here, from the basic formula of centripetal force and centrifugal force we get the direction of the force exerted on the object or body.

Formula used: $F = \dfrac{{m{v^2}}}{r}$
${F_c} = - \dfrac{{m{v^2}}}{r}$

Complete step by step answer:
Force acts differently on objects depending on the type of motion it exhibits. In case of curvilinear motion, there are two types of forces that act on an object:
1. Centripetal force: it is the force acting towards the center of the circular path.
It is mathematically expressed as:
$F = \dfrac{{m{v^2}}}{r}$
Here, F is the centripetal force, m is mass of the object, v is the speed or velocity of the object and r is the radius.
2. Centrifugal force is the force that acts in the direction pointing away from the centre of the circle.
It is mathematically expressed as:
${F_c} = - \dfrac{{m{v^2}}}{r}$
 Here, ${F_c}$ is the centrifugal force, m is the mass of the object, v is the speed or velocity of the object and r is the radius.
So, we can observe that centripetal force acts toward the centre and centrifugal force acts away from the centre.
Though same in magnitude and opposite in direction these forces do not form an action reaction pair i.e., Newton’s third law because they both act on the same object.

So, the correct answer is “Option A”.

Additional Information: Newton gave three laws of motion:
1. An object keeps on moving or in rest until and unless an external force is applied on the object.
2. The force on an object with acceleration a and mass m is given by: $F = m \times a$
3. For every action there is equal and opposite reaction
Centripetal and centrifugal forces both act on the same object, therefore action and reaction law is not applicable here.

Note: There are several motions of an object like straight line, rectangular, circular. Centripetal and centrifugal forces act only in circular motion of an object or body. Both the forces act in opposite directions.