U4 L3 Earth's Tides Online Lesson

Earth’s Tides

SC.8.N.1.1, SC.8.E.5.9

Unit 4 Lesson 3

WE WILL investigate what causes tides.
I WILL explain what tides are and what causes them in Earth’s oceans and describe variations in the tides.

Multiple Choice

What is the Moon's role in causing tides?

• Its phases make the tides rise and fall.

• Its gravity causes the water level on Earth to change.

• Its inertia works with its craters to make tides.

• It has no affect at all on Earth's tides.SCSC

Multiple Choice

What causes high tide on the side of the Earth opposite the Moon?

• The pull of the Sun on the side of the Earth opposite the Moon causes a high tide.

• The tilt of the Earth on its axis causes different seasons, such as spring which creates tides.

• The Moon pulls solid Earth toward itself, which makes the water bulge on the opposite side.

• The Oppositional Gravitational Force of the Moon pulls the water on the side farthest from itself.

What causes tides?

Tides = Daily changes in the level of ocean water.

Tides on Earth are caused mainly by the
pull of the moon’s gravity.

The sun’s gravity affects tides, although
not as strongly as the moon’s gravity.

The difference in gravitational force of the sun and moon across Earth is called the

tidal force.

water level is higher than the average sea level

High Tide

water level is lower than the average sea level

Low Tide

Multiple Choice

Which gravitational pull has the greatest effect on tides?

• the sun’s gravitational pull on Earth

• the moon’s gravitational pull on Earth

• Earth’s gravitational pull on the moon

• the sun’s gravitational pull on the moon

The difference between the levels of ocean water at high tide and low tide.

------------------------------------------------------------------For instance, if the height of the high tide is 2 m and the low tide is -1 m, the tidal range would be 3 meters.

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Use a number line to get an accurate range. How many jumps from high tide height to low tide height determines the range.

Tidal Range

Fill in the Blank

If the high tide is at 6 meters and the low tide is at 2 meters, the tidal range is how many meters?

• The largest daily tidal range

• Happens when the sun’s effect is added to the moon’s effect so that the tidal range is maximized. 

• Sun, Earth, and the moon form a straight line.

​Some text here about the topic of discussion.

Spring Tide

​Notice how the tidal ranges change with the different positions of the moon.

Multiple Choice

Which formula shows the effect of the sun and moon on spring tides?

• sun + moon = spring tides

• sun + Earth = spring tides

• sun - moon = spring tides

• Earth - moon = spring tides

• The smallest daily tidal range.

• Happens when the sun’s effect cancels the moon’s effect so that the tidal range is reduced. 

• Sun, Earth, and the moon are at a 90 degree angle.

​Some text here about the topic of discussion.

Neap Tide

Multiple Choice

How do the Sun and Moon work together to create a neap tide?

• by forming a right angle with Earth and creating an extreme gravitational pull

• by forming a right angle with Earth and canceling out each other's gravitational pulls

• by aligning on opposite sides of Earth and creating an extreme gravitational pull

• by aligning on opposite sides of Earth and canceling out each other's gravitational pulls

What causes tidal cycles?

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The rotation of Earth and the moon’s
revolution around Earth determine
when the tides occur.

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Most places on Earth have two low tides
and two high tides every day.

Because the moon revolves around Earth slower than Earth rotates, the cycle of tides is slightly longer than 24 hours. 

• Tide cycle happens in 24 hours and 50 minutes

• It takes 6 hours and 12.5 minutes for water to go from high to low tide. 

Can you explain why the tides happen 50 minutes later each day?

Tidal Cycles

Multiple Choice

How often does the moon pass over a particular spot on Earth’s surface, causing tides as a result of its gravitational pull?

• once every 10 seconds

• once every 12 hours and 25 minutes

• once every 24 hours and 50 minutes

• once every 14 days

Multiple Choice

Which of these is true about how often tides occur?

• All tides occur once a week.

• Tides have no pattern.

• High tides and low tides occur twice a month, and spring tides and neap tides occur twice a year.

• High tides and low tides occur twice a day, and spring tides and neap tides occur twice a month.