Have you ever heard that toilets flush in different directions depending on where you are in the world? Two popular science communicators, Veritasium and Smarter Every Day, teamed up to explore this idea. Let’s dive into what they discovered and the science behind it.
The experiment took place in Sydney, Australia, which is on the opposite side of the world from Huntsville, Alabama. The big question was whether toilets really flush in different directions in the Southern Hemisphere. Some people, including a famous episode of *The Simpsons*, say that toilets in Australia flush the opposite way. But is this true?
Many people think that the Coriolis effect makes water drain differently in each hemisphere. The Coriolis effect happens because the Earth spins, but it’s not the only thing that affects how water flows in small places like sinks or toilets. Other things, like how the water starts moving and the shape of the container, can also change the direction of the flow.
To test this idea, the team used a five-foot-wide kiddy pool. They filled it with water in an anticlockwise direction and left it alone for 24 hours to stop any initial motion. This way, they could see what happened when the pool was drained without any outside influences.
When they drained the pool, they added food coloring in four spots to see how the water moved. The water swirled clockwise, which matched what they expected for the Southern Hemisphere because of the Coriolis effect.
The experiment showed that the Coriolis effect does affect water flow, but it’s a small effect that can be overshadowed by other factors in smaller containers. The swirling motion in the pool happened because water at the outer edge moved faster than water near the center as it drained.
This is similar to why cyclones spin clockwise in the Southern Hemisphere. Air moves into the storm’s center, following the same directional patterns because of the hemisphere.
The collaboration between Veritasium and Smarter Every Day helped debunk the myth about toilet swirl. They explained that while the Coriolis effect does play a role, it’s usually too small to notice in everyday things like flushing toilets or draining sinks.
This exploration not only clears up a common misconception but also shows how important scientific inquiry and experiments are in helping us understand the world around us.
Gather materials like a large bowl, water, and food coloring. Fill the bowl with water and let it sit still for a few hours. Then, gently remove the plug and observe the direction of the swirl. Try this in different locations and note any differences. Discuss with your classmates how the Coriolis effect might influence your observations.
Create a map showing the Northern and Southern Hemispheres. Use arrows to indicate the typical direction of cyclones in each hemisphere. Discuss how the Coriolis effect influences these patterns and compare them to the experiment results from the article.
Use a rotating platform and a small container of water to simulate cyclone formation. Add a few drops of food coloring to visualize the motion. Spin the platform slowly and observe the direction of the swirl. Relate your findings to the Coriolis effect and how it impacts weather systems.
Divide into two groups and debate whether the Coriolis effect significantly impacts everyday water drainage. Use evidence from the article and your own research to support your arguments. Conclude with a discussion on how scientific inquiry helps debunk myths.
Work in pairs to calculate the Coriolis force using the formula $$F_c = 2m(v cdot omega)$$, where $m$ is mass, $v$ is velocity, and $omega$ is the angular velocity of the Earth. Discuss how this force compares to other forces acting on water in a sink or toilet.
Toilet – A device for disposing of human waste, often involving the use of water to flush the waste away. – In science class, we learned how the design of a toilet uses gravity to help water flow and remove waste efficiently.
Swirl – A circular pattern of motion, often seen in fluids like water or air. – When you drain the bathtub, you can see the water swirl as it moves towards the drain.
Coriolis – A force caused by the Earth’s rotation that affects the direction of moving objects, like wind and ocean currents. – The Coriolis force causes hurricanes to rotate counterclockwise in the Northern Hemisphere.
Effect – A change that is a result or consequence of an action or other cause. – The greenhouse effect is a warming of Earth’s surface due to the trapping of heat by greenhouse gases.
Water – A transparent, tasteless, odorless, and nearly colorless chemical substance, essential for all known forms of life. – Water boils at $100^circ$C under standard atmospheric pressure.
Flow – The movement of a fluid from one place to another. – The flow of electricity through a circuit can be compared to the flow of water through a pipe.
Experiment – A scientific procedure undertaken to test a hypothesis by collecting data and observing outcomes. – In our experiment, we measured how different surfaces affect the speed of a rolling ball.
Hemisphere – Half of a spherical object, often used to describe the division of Earth into Northern and Southern parts. – The Northern Hemisphere experiences summer when the Southern Hemisphere is in winter.
Science – The systematic study of the structure and behavior of the physical and natural world through observation and experiment. – Science helps us understand the laws of nature and how they apply to everyday life.
Motion – The action or process of moving or being moved. – Newton’s first law of motion states that an object at rest will stay at rest unless acted upon by an external force.
