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, creating 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 concept of centrifugal force becomes evident as the drum spins rapidly. As the drum rotates, the wet clothes inside experience an outward force, known as centrifugal force, that pushes them against the walls of the drum. This force helps to remove excess water from the clothes by pressing them outward, facilitating the escape of moisture. The combination of the spinning motion and the centrifugal force effectively wrings out the water from the clothes, resulting in a more efficient drying process. This application of centrifugal force in the clothes dryer showcases its ability to exert an outward push on objects in circular motion, influencing their behavior and contributing to practical everyday tasks.

Carousel

In the case of a carousel, its circular motion gives rise to centrifugal force, a pseudo force that emerges within a rotating frame of reference. As the carousel spins, this apparent force pushes riders outward, away from the center of rotation. This sensation creates an exhilarating experience, seemingly pulling them away from the center and creating a thrilling sense of acceleration. The centrifugal force acts in opposition to the centripetal force, which keeps the riders moving in their circular path. Together, these forces combine to create the dynamic and enjoyable ride that carousel-goers experience, adding an exciting element to the traditional amusement park attraction.

Train

When a train navigates a curved turn, centrifugal force comes into play to counteract the tendency of passengers to slide towards the inside of the curve due to inertia. This centrifugal force is a perceived outward push, experienced by passengers in the moving train, that seems to push them towards the outer side of the curve. In reality, it’s their inertia wanting to keep them moving in a straight line while the train curves. This apparent force ensures that passengers maintain a sense of stability and remain seated comfortably. It acts as a counterbalance to the centripetal force that keeps the train on its curved path. By exerting this outward force, centrifugal force helps enhance the safety and comfort of train travel, preventing passengers from experiencing sudden shifts or jolts as the train negotiates curves.

Jet aircraft

As a jet aircraft completes a loop, centrifugal force comes into play to counteract the force of gravity. During the loop, the aircraft and its pilot experience a rapid change in direction, causing them to accelerate towards the center of the loop’s curvature. This acceleration generates a centrifugal force that pushes the pilot against their seat, effectively preventing them from falling out of the aircraft despite the pull of gravity. The combination of this outward force and the aircraft’s aerodynamic design ensures that the pilot remains firmly seated and securely in control throughout the maneuver.

Bicycle tire

When a bicycle tire is stuck in mud and begins to rotate, the circular motion generates centrifugal force that influences the mud trapped within the tire’s tread. As the tire spins, the mud experiences an outward push due to the centrifugal force. This outward push causes the mud to be flung off the tire and propelled in a radial direction away from the center of rotation. The faster the tire rotates, the stronger the centrifugal force becomes, resulting in more mud being expelled. This phenomenon is a result of the tire’s rotation creating a dynamic interplay between its motion and the mud’s inertia, showcasing the effect of centrifugal force in action.

Water bucket

When a water bucket is spun in a circular motion, such as when swinging it around in a vertical circle, centrifugal force comes into play. As the bucket rotates, the water inside it experiences an outward push due to the centrifugal force. This outward force is a result of the water’s inertia, which tends to make it continue moving in a straight line, even as the bucket curves around. The centrifugal force is directed away from the center of rotation, which in this case is the axis around which the bucket is spun. This outward push of centrifugal force counteracts the gravitational pull on the water, allowing the water to be held inside the bucket despite being upside down at the top of its circular path. This phenomenon illustrates how centrifugal force can have a noticeable effect on objects in circular motion, working against gravity to maintain the contents within the spinning container.

Centrifugal pump

In a rotating centrifugal pump, the principle of centrifugal force is employed to move fluids efficiently. The pump consists of an impeller that spins rapidly within a housing. As the impeller rotates, it imparts centrifugal force to the fluid present in the pump. This force causes the fluid to be pushed outward, away from the center of rotation, towards the outer edges of the impeller. As the fluid moves outward, it gains kinetic energy due to the increase in velocity. This kinetic energy results in pressure differences within the pump, creating a pressure gradient that drives the fluid through the pump’s outlet. The centrifugal force generated by the impeller’s rotation plays a crucial role in the fluid’s movement, enabling the pump to transport liquids effectively and enhancing its overall pumping efficiency.

Centrifugal governor

Centrifugal governors are devices used to regulate the speed of engines by harnessing the power of centrifugal force. These mechanisms consist of rotating weights that are connected to the engine’s throttle. As the engine speed increases, the rotating weights experience an outward force due to their circular motion. This centrifugal force causes the weights to move away from the central axis of rotation. When the weights move outward, they actuate the throttle, reducing the fuel supply to the engine. In contrast, when the engine speed decreases, the centrifugal force on the weights diminishes, allowing them to move inward and open the throttle, thus increasing the fuel supply. This ingenious application of centrifugal force allows 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. Denoted by Fc, this force represents the apparent push away from the center, arising 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, arising 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 velocity 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 velocity 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 velocity 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 velocity 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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