Centrifugal force

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Centrifugal force, also known as a fictitious or pseudo force, is the force that appears to act on all objects when viewed from a rotating frame of reference. For instance, on a merry-go-round, individuals seated experience an outward force due to the rotation, which creates the sensation of being pushed away from the center. This phenomenon arises because the rotating frame imparts an apparent acceleration to objects, causing them to move away from the center of rotation. It’s important to note that centrifugal force is not an actual force but rather a perception that arises due to the choice of a rotating reference frame.

Examples

Clothes dryer

In a clothes dryer, the effect of centrifugal force becomes apparent as the drum spins rapidly. As the drum rotates, the wet clothes inside experience an apparent outward force, often referred to as centrifugal force, which pushes them against the walls of the drum. This outward push helps to remove excess water by forcing it out of the fabric and facilitating its evaporation. The combination of the spinning motion and this centrifugal effect enhances the efficiency of the drying process, effectively wringing out water from the clothes. This application of centrifugal force in the clothes dryer demonstrates how rotational motion can influence the behavior of objects, contributing to practical everyday tasks like drying clothes.

Bicycle tire

When a bicycle tire is stuck in mud and is forced to rotate, the rotation creates an effect that can be perceived as centrifugal force. As the tire spins, the mud trapped within the tire’s tread experiences an outward push due to its inertia. This apparent centrifugal force causes the mud to be flung off the tire, moving radially away from the center of rotation. The faster the tire rotates, the greater the apparent force, resulting in more mud being expelled. This effect is a result of the tire’s rotation and the mud’s resistance to change in its state of motion, illustrating how inertia and rotational dynamics influence the behavior of the mud.

Centrifugal pump

In a rotating centrifugal pump, the principle of centrifugal force is utilized to move fluids efficiently. The pump contains an impeller that spins rapidly within a housing. As the impeller rotates, it imparts centrifugal force to the fluid inside the pump. This apparent force causes the fluid to be pushed outward, away from the center of rotation, toward the outer edges of the impeller. As the fluid moves outward, it gains kinetic energy due to the increase in velocity. This kinetic energy creates pressure differences within the pump, resulting in a pressure gradient that drives the fluid through the pump’s outlet. The centrifugal effect generated by the impeller’s rotation is essential for the fluid’s movement, enabling the pump to transport liquids effectively and enhancing its overall efficiency.

Centrifugal governor

Centrifugal governors are devices used to regulate engine speed by utilizing the principle of centrifugal force. These mechanisms consist of rotating weights connected to the engine’s throttle. As the engine speed increases, the rotating weights experience an outward force due to their circular motion. This apparent centrifugal force causes the weights to move away from the central axis of rotation. As the weights move outward, they actuate the throttle, reducing the fuel supply to the engine. Conversely, when the engine speed decreases, the centrifugal force on the weights lessens, allowing them to move inward and open the throttle, thereby increasing the fuel supply. This clever application of centrifugal force enables centrifugal governors to effectively control and maintain a steady engine speed, ensuring optimal performance and efficiency.

Equation

The centrifugal force equation, expressed as Fc = (m × v2) ÷ r, calculates the outward force experienced by an object moving in a curved path. This force, denoted by Fc, represents the apparent push away from the center that arises in a non-inertial reference frame. The variables m, v, and r represent the mass of the object, its velocity, and the radius of the curved path, respectively. It’s important to note that the centrifugal force is a pseudo or fictitious force that arises only due to the object’s inertia in the rotating frame of reference and not from any actual force acting on the object.

Practice problems

Problem #1

A pendulum bob weighing 0.1 kg swings in a circular path with a radius of 0.5 meters and a speed of 2 m/s. Calculate the centrifugal force exerted on the pendulum bob during its swinging motion.

Solution

Given data:

  • Mass of the pendulum bob, m = 0.1 kg
  • Radius of the circular path, r = 0.5 m
  • Velocity of the pendulum bob, v = 2 m/s
  • Centrifugal force acting on the pendulum bob, Fc = ?

Using the equation:

  • Fc = (m × v2) ÷ r
  • Fc = [0.1 × (2)2] ÷ 0.5
  • Fc = 0.4 ÷ 0.5
  • Fc = 0.8 N

Therefore, the centrifugal force acting on the pendulum bob is 0.8 N.

Problem #2

A drone with a mass of 2.5 kg moves in a circular path with a radius of 25 meters and a speed of 10 m/s. What is the magnitude of the centrifugal force acting on the drone?

Solution

Given data:

  • Mass of the drone, m = 2.5 kg
  • Radius of the circular path, r = 25 m
  • Velocity of the drone, v = 10 m/s
  • Centrifugal force acting on the drone, Fc = ?

Using the equation:

  • Fc = (m × v2) ÷ r
  • Fc = [2.5 × (10)2] ÷ 10
  • Fc = 250 ÷ 10
  • Fc = 25 N

Therefore, the centrifugal force acting on the drone is 25 N.

Problem #3

A gymnast weighing 60 kg performs on a rotating platform with a radius of 3 meters and a speed of 5 m/s. Determine the centrifugal force experienced by the gymnast during the performance.

Solution

Given data:

  • Centrifugal force acting on the gymnast, Fc = ?
  • Mass of the gymnast, m = 60 kg
  • Velocity of the gymnast, v = 5 m/s
  • Radius of the circular path, r = 3 m

Using the equation:

  • Fc = (m × v2) ÷ r
  • Fc = [60 × (5)2] ÷ 3
  • Fc = 1500 ÷ 3
  • Fc = 500 N

Therefore, the centrifugal force acting on the gymnast is 500 N.

Problem #4

A spaceship weighing 5000 kg orbits in a circular path with a radius of 1000 meters and a speed of 8000 m/s. Find the centrifugal force acting on the spaceship in its orbital motion.

Solution

Given data:

  • Mass of the spaceship, m = 5000 kg
  • Radius of the circular path, r = 1000 m
  • Velocity of the spaceship, v = 8000 m/s
  • Centrifugal force acting on the spaceship, Fc = ?

Using the equation:

  • Fc = (m × v2) ÷ r
  • Fc = [5000 × (8000)2] ÷ 1000
  • Fc = (320 × 109) ÷ 1000
  • Fc = 320 × 106 N

Therefore, the centrifugal force acting on the spaceship is 320 × 106 N.

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Deep

Forceinphysics.com was founded by Deep Rana, who is a mechanical engineer by profession and a blogger by passion. He has a good conceptual knowledge on different educational topics and he provides the same on this website. He loves to learn something new everyday and believes that the best utilization of free time is developing a new skill.

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