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Tidal Forces

Short answer: The Moon's gravity pulls the ocean into a bulge on the side facing it, and a second bulge forms on the far side because the Moon pulls Earth's center more strongly than the far ocean.

As Earth rotates through both bulges, most coasts see two high and two low tides in about 24 hours and 50 minutes, a lunar day. The Sun's gravity adds smaller tides. The footage, credited to explainingtheuniverse, shows an animation of Earth's tidal bulges.

VideoWrite-up1 sources
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What should you know about Tidal Forces?

Quick facts. Each one stands alone and has a stable ID you can cite.

  1. Moon's gravity.

    DD-544-F01 · Write-up · Exhibit A (Cause)

  2. Two.

    DD-544-F02 · Write-up · Exhibit B (Bulges)

Video transcript: Tidal Forces: The Moon Raises Ocean Bulges on Both Sides of Earth

Did you know, the moon affects Earth's tides through its gravitational pull, which causes the oceans to bulge slightly on the side facing the moon, and also on the opposite side due to inertia. These bulges create high tides, while the areas at 90 degrees to the moon experience low tides. As the Earth rotates, different coastal regions pass through these bulges, resulting in two high tides and two low tides roughly every 24 hours. NOW YOU KNOW!

Burned-in captions, read frame by frame (see transcript.md) · 21.2s Reel ·

Video coming soonTidal Forces · Instagram Reel
Tidal Forces: The Moon Raises Ocean Bulges on Both Sides of Earth Instagram Reel · · 21.2s

The write-up

The Moon raises ocean bulges on both sides of Earth. Most coasts get two high tides a day.

  1. Exhibit A

    Cause

    Moon's gravity.

  2. Exhibit B

    Bulges

    Two.

  3. Exhibit C

    Cycle

    About 24 h 50 min.

  4. Exhibit D

    Lows

    At 90 degrees.

  5. Exhibit E

    Sun

    Smaller effect.

Questions people ask about Tidal Forces

How many bulges?

Both sides.

Source: Write-up · Exhibit A (Cause) · Wikipedia: Tide

Tidal day?

Lunar.

Source: Write-up · Exhibit B (Bulges) · Wikipedia: Tide

Main cause?

Pull.

Source: Write-up · Exhibit C (Cycle) · Wikipedia: Tide

Low tides occur?

Between.

Source: Write-up · Exhibit D (Lows) · Wikipedia: Tide

Also contributes?

Smaller.

Source: Write-up · Exhibit E (Sun) · Wikipedia: Tide

Test Your Knowledge

All quizzes →

5 questions, all from this case file. Answers are revealed instantly.

  1. How many bulges?

    1. Two
    2. One
    3. Four
    4. None
    Show the answer

    Answer: A. Two Both sides. Source: Write-up · Exhibit A (Cause) · Wikipedia: Tide

  2. Tidal day?

    1. About 24 h 50 min
    2. 12 h
    3. 7 days
    4. 1 hour
    Show the answer

    Answer: A. About 24 h 50 min Lunar. Source: Write-up · Exhibit B (Bulges) · Wikipedia: Tide

  3. Main cause?

    1. Moon's gravity
    2. Wind
    3. Earthquakes
    4. Rivers
    Show the answer

    Answer: A. Moon's gravity Pull. Source: Write-up · Exhibit C (Cycle) · Wikipedia: Tide

  4. Low tides occur?

    1. At 90 degrees
    2. Under the Moon
    3. At poles only
    4. Never
    Show the answer

    Answer: A. At 90 degrees Between. Source: Write-up · Exhibit D (Lows) · Wikipedia: Tide

  5. Also contributes?

    1. The Sun
    2. Mars
    3. Jupiter
    4. Comets
    Show the answer

    Answer: A. The Sun Smaller. Source: Write-up · Exhibit E (Sun) · Wikipedia: Tide

Cite this case file

Easterling, Marcus. "Tidal Forces." The Detail Department (DetailEnjoyer), case file DD-544, last updated Apr 15, 2025. https://detailenjoyer.com/case/tidal-forces/

Permalink: https://detailenjoyer.com/case/tidal-forces/ · Last updated

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