How Physicists FINALLY Solved the Feynman Sprinkler Problem - Explained
TLDRThe Fineman sprinkler problem, a physics mystery that puzzled scientists for over 140 years, has finally been addressed. Researchers, including Richard Feynman, debated whether a sprinkler submerged in water and sucking water in would spin forward or backward. After meticulous experimental design and innovative techniques, it was discovered that the sprinkler does indeed spin, but in the reverse direction compared to a conventional sprinkler. The study revealed that the rotational torque is caused by the variable velocity profile of inward jets within the sprinkler system, leading to a slow but observable rotation.
Takeaways
- π§ The Fineman sprinkler problem involves a sprinkler submerged in water with the pump reversed, causing debate on whether it spins forward, backward, or not at all.
- π Newton's third law is key to understanding the normal operation of a sprinkler, where water exiting creates a reaction force that spins the sprinkler head.
- π The problem has puzzled physicists for over 140 years, including renowned scientist Richard Feynman.
- π The sprinkler's spin direction when submerged and sucking in water was ultimately determined through meticulous experimental design and fluid dynamics analysis.
- π¦ The experiment used a gravity-powered siphon system to avoid pump-induced vibrations and a near frictionless bearing system using water's meniscus effect.
- π¬ Visualization of water flow was achieved with hollow glass microparticles and a green laser, revealing the sprinkler's slow reverse spin.
- π The Fineman sprinkler spins in reverse due to the asymmetrical vortex shape created by the collision of two inward jets within the sprinkler system.
- π Particle Image Velocimetry (PIV) confirmed variable velocity profiles within the inward jets, contributing to the rotational torque.
- π The research paper provides in-depth explanations, combining visual, logical, intuitive, and mathematical descriptions of the system's behavior.
- π Even simple concepts can be deceptively complex, as demonstrated by the Fineman sprinkler problem.
- π₯ The final video of the sprinkler rotating in reverse serves as a compelling conclusion to a problem that has stood for over a century.
Q & A
What is Newton's third law as it relates to the sprinkler system?
-Newton's third law states that for every action, there is an equal and opposite reaction. In the context of the sprinkler system, this law explains that the force of the water exiting the sprinkler arms causes the sprinkler head to spin in the opposite direction to the water's movement.
What happened when Richard Feynman attempted to solve the sprinkler problem?
-When Richard Feynman attempted to solve the sprinkler problem, he submerged a sprinkler into water and applied a pump to pull water through the system. He observed a brief moment of movement but concluded that the pump wasn't working hard enough to make that movement anything more than a momentary bump. He then increased the pressure, which resulted in the pump breaking and causing water, broken glass, and cloud chamber images to be ruined.
How did the concept of the Fineman sprinkler come about?
-The concept of the Fineman sprinkler originated in 1883 when physicist and philosopher Ernst Mark published the first known description of the reverse sprinkler problem. He discovered that a central spindle connected to C-shaped arms would spin away from the exit hole where the air was pumped through. However, when he let go of the hand pump, the apparatus sucked air back in but did not cause the system to rotate in the opposite direction.
What were the different theories proposed by Feynman's students regarding the sprinkler's rotation when suction is applied?
-Feynman's students proposed three different theories: some thought that suction would create a low-pressure zone and draw the sprinkler arm towards it, causing the sprinkler to spin backwards; others believed that the forward momentum imparted to the water molecules at the corner of the sprinkler arm would cancel out the reverse suction, causing the sprinkler not to move at all; and a third group suggested that suction from all directions at the entry point would be a small overall force, and the forward momentum would dominate, causing the sprinkler head to rotate forwards.
How did the researchers avoid the issue of experimental design inconsistencies in previous attempts to solve the Fineman sprinkler problem?
-The researchers avoided inconsistencies by using a siphon connected to the top of the sprinkler, which was powered by gravity rather than a liquid pump, to maintain a constant height difference between two water containers. They also used water itself as the bearing system to reduce bearing friction and employed a laser sheet imaging technique with hollow glass microparticles to visualize the flow of water through the system.
What is the significance of the meniscus effect in the experimental setup?
-The meniscus effect is significant in the experimental setup because it creates a near frictionless bearing system. The researchers used the concave meniscus effect inside a cylinder combined with the convex type created by floating the sprinkler head apparatus underneath the water, which allowed for the sprinkler to rotate with minimal resistance.
What was observed when the researchers immobilized the sprinkler and studied the system?
-When the researchers immobilized the sprinkler and studied the system, they observed an odd, slightly asymmetrical full Vortex shape forming in the center of the sprinkler as water entered the central cavity. This vortex was created by the collision of two inward jets, with centrifugal effects leading to higher velocity flows on the edges of the tubes.
How does the Dean flow problem relate to the Fineman sprinkler system?
-The Dean flow problem, which involves flow within thin curved pipes, is related to the Fineman sprinkler system as it explains the variable velocity profile over the width of the inward jets. Centrifugal effects lead to higher velocity flows on the edges of the tubes, which contributes to the rotational torque on the system and ultimately causes the sprinkler to spin in reverse.
What was the final conclusion of the researchers regarding the Fineman sprinkler's rotation?
-The researchers concluded that the Fineman sprinkler spins in reverse due to the remaining rotational force from the inward jets, which have a variable velocity profile over their width. This small force causes the system to spin at about 40 times slower than a conventional sprinkler system, confirming Mark's original observation but also revealing the mechanism behind it.
How did the researchers visualize the flow of water in the reverse sprinkler system?
-The researchers used hollow glass microparticles to scatter light and a 1-watt green laser to illuminate them. They employed a cylindrical lens to spread the laser into a line, a technique known as laser sheet imaging, which is widely used to observe events happening in a slice of liquid or gas.
What is the significance of the Fineman sprinkler problem in the context of fluid dynamics?
-The Fineman sprinkler problem is significant in fluid dynamics as it demonstrates the complexity of seemingly simple concepts. It shows how small forces and subtle interactions within a system can lead to unexpected outcomes, highlighting the intricate nature of fluid flow and the challenges in accurately predicting and understanding such systems.
Outlines
π§ The Fineman Sprinkler Mystery
This paragraph introduces the Fineman sprinkler problem, a scientific puzzle that has perplexed physicists for over 140 years. It describes how a sprinkler operates based on Newton's third law, with water's momentum causing the sprinkler to spin. The central question is what would happen if the sprinkler was submerged and water was sucked in instead of pushed out. The paragraph also recounts the history of the problem, starting with Ernst Mark in 1883 and leading to Richard Feynman's unsuccessful attempt to solve it. The narrative sets the stage for a detailed exploration of the problem and the innovative techniques used to study it.
π Understanding Momentum Transfer
This paragraph delves into the mechanics of how a sprinkler spins, focusing on the transfer of momentum from the water to the sprinkler head. It explains that the momentum transfer occurs at the sidewall of the sprinkler arm, where the water provides a tangential force that causes the sprinkler to rotate. The paragraph also discusses the variety of shapes and sizes of sprinklers and how the basic principle of momentum transfer applies to them. It then addresses the complexity introduced by fluid mechanics and the debate among physicists regarding the direction the sprinkler would spin when water is sucked through the system.
π§ͺ Experimenting with the Submerged Sprinkler
This paragraph describes the experimental setup designed to test the Fineman sprinkler problem. It outlines the challenges faced in previous attempts, such as the influence of pump vibrations and bearing friction, and how the researchers overcame these issues. The innovative design used gravity and a siphon system to power the sprinkler, eliminating the need for a mechanical pump. The paragraph also explains how the researchers used water as a bearing system, taking advantage of meniscus effects to achieve near frictionless movement. The experimental visualization involved using hollow glass microparticles and a green laser to track the water flow, providing insights into the sprinkler's behavior when reversed.
π Unraveling the Reverse Rotation
This paragraph reveals the results of the experiment and the underlying physics that cause the Fineman sprinkler to spin in reverse when water is sucked through it. The researchers observed the formation of vortices and used Particle Image Velocimetry (PIV) to analyze the flow. They found that the inward jets of water had a variable velocity profile, with higher velocities on the edges, leading to a rotational torque that spins the sprinkler in the opposite direction. The paragraph emphasizes the complexity of the system and how a small force can have significant effects. It concludes with a qualitative description of the angular momentum flux and the rotational dynamics involved.
πΏ The Implications of the Fineman Sprinkler
The final paragraph reflects on the significance of the Fineman sprinkler research, highlighting how a seemingly simple concept can be much more complex than it appears. It praises the paper for its comprehensive approach, combining visual, logical, intuitive, and mathematical explanations. The paragraph also touches on the broader implications of the research, reminding us that even the greatest scientific minds can be stumped by complex phenomena. It ends with a call to action for viewers to engage with the content and explore other related research, such as how plants communicate through fluorescence.
Mindmap
Keywords
π‘Newton's third law
π‘Sprinkler
π‘Momentum transfer
π‘Richard Feynman
π‘Dean flow
π‘Vortices
π‘Friction
π‘Siphon
π‘Particle image velocimetry (PIV)
π‘Laser sheet imaging
π‘Angular momentum flux
Highlights
The Fineman sprinkler problem, a mystery that has puzzled physicists for over 140 years, has finally been solved.
The sprinkler's spinning action is due to Newton's third law, which states that for every action, there is an equal and opposite reaction.
The Fineman sprinkler effect occurs when a sprinkler is submerged in water and the pump direction is reversed, causing the sprinkler to suck in water instead of pushing it out.
Richard Feynman, one of the greatest minds in science, attempted to solve the Fineman sprinkler problem but was unsuccessful.
The initial understanding of the sprinkler's behavior was published by physicist Ernst Mark in 1883, who found that the sprinkler did not rotate when air was sucked back in.
Princeton physics students debated the Fineman sprinkler problem 60 years after Mark's initial findings, suggesting that the sprinkler should spin in reverse or not at all.
Feynman's experiment with the submerged sprinkler led to a brief moment of movement, but he concluded the pump wasn't strong enough, leading to a dramatic accident with broken glass and a ruined cloud chamber.
The momentum transfer from exiting water is what causes a normal sprinkler to spin, with the force imparted at the sidewall of the sprinkler arm.
The Fineman sprinkler spins in the reverse direction when water is sucked through the system, due to a small rotational torque created by the asymmetrical vortex shape within the sprinkler.
The researchers used a siphon system powered by gravity to avoid the vibrations and fluctuations caused by liquid pumps, ensuring consistent experimental results.
Friction was minimized by using water itself as the bearing system, leveraging the meniscus effect to achieve near frictionless movement.
The experimental setup included a laser sheet imaging technique using hollow glass microparticles and a green laser to visualize the water flow.
The Fineman sprinkler spins approximately 40 times slower than a conventional sprinkler system due to the low consequential force.
The Dean flow problem, which studies flow within thin curved pipes, provides insight into the variable velocity profile over the width of the inward jets contributing to the sprinkler's rotation.
The research team, led by Kae Wang, used innovative experimental design and visualization techniques to finally settle the Fineman sprinkler debate.
The Fineman sprinkler problem is an example of how a seemingly simple concept can be far more complex than initially appears, challenging even the greatest scientific minds.
The study's authors provided both qualitative and mathematical explanations, demonstrating the complexity of the system and the depth of their research.
The Fineman sprinkler's slow rotation in the reverse direction was captured in a final video, showcasing theη η©Άζζ of the researchers' efforts.
Transcripts
Browse More Related Video
The Logistics of Firefighting
Arc Length and Area of a Sector | Formulas | Sample Problems | Trigonometry | Pre-Calculus
Angular Motion and Torque
Scalar field line integral independent of path direction | Multivariable Calculus | Khan Academy
Kugelpanzer Ball Tank (Strangest Tanks in History)
The Right Hand Rule for Torque
5.0 / 5 (0 votes)
Thanks for rating: