Tides

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Tides
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1. Tides-What are they?
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Mont Saint Michel France
http//www.weather.com/video/stunning-places-to-vi
sit-at-low-tide-39407
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Tides

• Tides are the regular rise and fall of ocean
  water levels.

http//www.youtube.com/watch?v__UEYLfLL3c
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2. What causes tides to occur?

• Tides are due to the gravity of the moon trying
  to pull the water on Earth closer to it (the
  moon).

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What causes tides to occur?

• The sun also pulls on the water, but it is
  farther away, so it doesnt have as much as an
  effect.

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Gravitational Pull

• Gravitational pull depends on the mass of the
  object and its distance from Earth

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What would happen to our high tides if the moon
were more massive (bigger)?
Tides would be higher because the moon would have
a greater gravitational pull on them
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What would happen to our tides if the moon were
further away?

• Tides would be smaller because of less
  gravitational pull

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What would happen to our tides if the moon were
closer?
http//www.youtube.com/watch?voBDZtt0vWD8

• Tides would be larger because of more
  gravitational pull

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• Life as We Knew It
• Summary
• A family describes what life would be like on
  Earth if the moon were hit by a meteorite and
  pushed closer.

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Earth rotates every 24 hours, which means that
the places on Earth where high tide and low tide
occur are always changing.
http//www.astro.umass.edu/arny/images/tidemov.gi
f
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Watch the tide change in Africa
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High Tide to Low Tide takes about 6 ¼ hours

• Knowing this will help you set up your beach
  chair in the right place!

http//www.youtube.com/watch_popup?vZ0qGvC3vqaA (
fishing under ice at low tide)
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3. Spring Tide

• When the Earth, Sun, and Moon are in a straight
  line (new moon and full moon) their gravitational
  force is combined and you have extra high and
  extra low tides called Spring Tides

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4. Neap Tides

• When the Sun, Earth, and Moon are at a right
  angle (1st and 3rd Quarter) the gravitational
  pull is not as strong and tides are not as high
  or low as normal, this is called a Neap Tide.

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Review Questions
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If low tide is at 9am, when will high tide happen?

• Add 6 ¼ hours (6 hours and 15 minutes)
• 315pm

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If high tide is at 8pm, when would the next high
tide occur?

• Add 6 ¼ hours to get to low tide
• Then add another 6 ¼ hours to get back to high
  tide.
• 830am

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Which diagram produces the highest tides? Explain

• B Because the moon is in a new moon phase and
  the moon and suns gravitational pull are
  combined.

A
B
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If the moon were closer, what would be the effect
on our tides?

• Higher tides because a closer moon would have
  more gravitational pull

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If the moon were larger, what would be the effect
on our tides?

• Higher tides because a larger moon would have a
  greater gravitational pull.