How the tides REALLY work

Summary

This educational video delves into the science of tides, debunking common misconceptions and explaining the gravitational forces behind their rhythmic fluctuations. It clarifies that tides are caused by the moon's gravitational pull, which deforms Earth's shape, creating bulges on the near and far sides. The video further explores how these forces, influenced by the moon, sun, and other celestial bodies, result in complex tidal patterns that vary by location, with a special focus on the Bay of Fundy's extreme tidal range due to its unique geography.

Takeaways

• 🌊 Tides are the rhythmic changes in the water level of the ocean, and they are often misunderstood despite being a common phenomenon.
• 🌕 The common explanation of tides involving the moon's gravitational pull creating a bulge in the ocean is incomplete and oversimplified.
• 📚 Newton's law of universal gravitation and his second law of motion are fundamental to understanding the true nature of tides.
• 🪐 The gravitational force between two objects is proportional to their masses and inversely proportional to the square of the distance between them.
• 🚀 Newton's second law shows that the acceleration of an object due to gravity is independent of its own mass, which is key to understanding tidal forces.
• 🌍 The Earth's rotation and the gravitational pull of the moon cause water on the near and far sides of the Earth to bulge, forming high tides.
• 🌊 Tidal forces can deform celestial bodies, including the Earth's moon, which has an elliptical shape due to Earth's gravitational influence.
• 🌞 Tides on Earth are primarily influenced by the moon, but other massive bodies like the sun also contribute to tidal forces.
• 📉 The distance a celestial body is from Earth has a greater impact on tidal forces than its mass, due to the square law in gravitational attraction.
• 🌊 Different tidal constituents, such as M2 and S2, represent different periodic tidal patterns caused by the moon and the sun.
• 🌌 Spring and Neap tides are significant alignments of tidal forces that result in higher or lower than usual tides, respectively.
• 🏞 The Bay of Fundy exemplifies how local geography can amplify tidal effects, leading to extreme tidal ranges due to resonance.

Q & A

What are tides and why are they commonly misunderstood?

Tides are the rhythmic changes in the water level of the ocean that occur daily. They are commonly misunderstood because the intuitive explanation of the moon's gravitational pull creating a bulge in the ocean is often oversimplified and does not fully explain the phenomenon, leading to misconceptions.

What is the role of the moon in creating tides?

The moon's gravitational force pulls water towards it, creating a bulge in the ocean known as high tide. However, the moon's influence is more complex than just creating a bulge on the side closest to it; it also affects the water on the opposite side due to the distance dependency of gravity.

What is Newton's law of universal gravitation and how does it relate to tides?

Newton's law of universal gravitation states that the gravitational force between two objects is proportional to the product of their masses and inversely proportional to the square of the distance between their centers. This law is key to understanding tides, as it explains how the moon's gravity affects the Earth's water.

How does Newton's Second Law relate to the acceleration of celestial bodies towards each other?

Newton's Second Law, expressed as F=MA, states that the acceleration of an object is directly proportional to the net force acting upon it and inversely proportional to its mass. This principle explains how celestial bodies, like planets, accelerate towards each other due to gravitational forces.

What is the tidal force and how does it affect the shape of celestial bodies?

The tidal force is a result of gravitational fields that deform the shape of celestial bodies, causing them to stretch and form an elliptical shape. This force is responsible for the creation of tides in the ocean and can even lead to the deformation or disintegration of celestial bodies if the tidal force is strong enough.

Why do the tides on Earth have two bulges instead of just one?

The tides on Earth have two bulges because the water on the near side of the Earth accelerates faster towards the moon than the solid rock in the middle, creating a bulge. Simultaneously, the water on the far side accelerates slower, forming a second bulge as it is effectively left behind by the accelerating rock.

What is the Roche limit and how does it relate to tidal forces?

The Roche limit is the closest distance a celestial body can orbit another without being torn apart by the tidal force. It is a calculable metric in astronomy that helps understand the stability of orbits and the potential for tidal disruption.

How do the tides vary in different parts of the world?

Tides vary in different parts of the world due to the shape of the coastline, local bathymetry, and the alignment of tidal forces. Some areas, like the Bay of Fundy, can experience extreme tidal ranges due to resonance effects, while other areas may have more moderate changes.

What are tidal constituents and how do they contribute to the complexity of tides?

Tidal constituents are the sinusoidal patterns that make up the tidal signal, each with its own frequency and amplitude. They are influenced by the gravitational forces of the moon, sun, and other celestial bodies. The complexity of tides arises from the interaction and alignment of these constituents throughout the year.

What are Spring and Neap Tides, and how do they differ?

Spring tides occur when the moon and sun are aligned, causing their gravitational forces to combine and result in higher high tides and normal low tides. Neap tides happen when the moon and sun are at a 90-degree angle to each other, leading to a misalignment of their tidal forces and creating lower high tides and higher low tides.

Why don't lakes and ponds exhibit noticeable tidal changes like the ocean?

Lakes and ponds have tides, but they are not as noticeable because they are isolated bodies of water with less water volume to move around and create significant changes. The tides in these bodies of water are too small for us to easily observe.

How can local knowledge from sailors, fishers, and surfers enhance our understanding of tides?

Local knowledge from those who observe the ocean daily can provide unique insights into the specific tidal patterns of a region. This knowledge is invaluable as it accounts for the unique geographical and environmental factors that influence tides in different areas.