If the distance from the moon to the Earth decrease from 230,000 miles (which it is today) to 20,000 miles, what affect would this have on the tides?
With the closer distance, its gravitational pull will have a greater effect on the the tides.
To determine the effect of a change in distance between the moon and the Earth on tides, we need to understand the basic mechanism behind tides. Tides are caused by the gravitational pull of the moon and the sun on Earth's oceans. As the moon orbits around the Earth, it exerts gravitational force on the water on the side nearest to it, creating a high tide. At the same time, the water on the opposite side of the Earth experiences a high tide due to the centrifugal force caused by the Earth–moon system. The areas in between experience low tides.
Now, if the distance from the moon to the Earth decreases from 230,000 miles to 20,000 miles, it means that the moon will be much closer to Earth than normal. This change will have a significant impact on the tides.
The gravitational force between two objects is inversely proportional to the square of the distance between them. So, if the distance decreases, the gravitational force will increase. In this case, the moon's gravitational force on the Earth's oceans would be much stronger than usual.
Therefore, with the moon so close, we can expect to see much higher tides than normal. The increased gravitational force from the closer proximity will cause the oceans to rise higher during high tide and fall lower during low tide. These increased tides are often referred to as "spring tides."
It is important to note that tides are influenced by other factors, such as the position of the sun and the shape of coastlines. But, assuming these factors remain constant, the decrease in distance between the moon and the Earth would result in higher and more pronounced tides.