8.7 c tides

8.7 C Tides

Multiple Choice

But first look at the picture and answer below

• F

• G

• H

• J

The Moon and Tides

• The moon is also important to us because it creates tides. 

• Tides are daily movements of ocean water that change the level of the ocean's surface.

• Tides are causes by: the exertion of gravitational forces by the moon and sun

• The relationship between the phases of the moon and the tides was discovered by a Greek explorer named Pytheas.

• Even though the moon is much smaller than the sun, it is the moon's gravity that is the force behind the Earth's tides

Multiple Choice

Is the Sun or the Moon more responsible for the Earth's tides?

• Sun

• Moon

High Tide

• Everything on Earth is pulled on by the gravity of the moon. When that part of the Earth happens to include an ocean, the water there rushes toward the moon.

• Because liquids move more easily, the pull of gravity is much more noticeable in liquids than in solids.

• The moon's pull is strongest on the part of the Earth directly facing the moon.

• At the same time, water on the opposite side of the Earth bulges due to inertia caused by the motion of the Earth and moon around each other.

• These bulges are what we call high tides.

Multiple Choice

When the moon's pull is strongest on the part of the Earth directly facing the moon what kinds of tides occur?

• High Tide

• Low Tide

Low Tide

• Notice that when high tides occur, water is drawn away from the area between the high tides, causing low tides.

• Two high tides and two low tides occur each day.

• The ocean is constantly cycling from high tide to low tide and then back to high tide.

• There is about 12 hours and 25 minutes between the two high tides.

Multiple Choice

How many high and low tides occur each day?

• 1

• 2

• 3

• 4

The Sun and the Tides

• The sun is the second factor that affects tides.

• However, the sun does not have as much influence on the tides as the moon does because it’s farther away. 

• Tidal ranges are based on the position of the Earth, moon, and sun.

Multiple Choice

What are tidal ranges based off of?

• The Sun

• The moon

• The earth

• all of the above

Spring Tides

• Spring tides occur when the Earth, the sun, and the moon are in a line. The name spring tide has nothing to do with the season.

• Spring tides occur during the full moon and the new moon.

• These are very strong tides and occur every 14 days.

• The diagrams below show the two situations in which spring tides occur.

Multiple Choice

When do spring tides occur

• New moon

• Full moon

• Both

Neap Tides

• Neap tides which are very weak tides, occur during this time.

• During this time, the gravitational forces of the moon and sun are perpendicular to each other which cause the pulls to "cancel out" each other.

• The diagrams below show the two situations in which neap tides occur.

Multiple Choice

Are neap tides weak or strong

• Strong

• Weak

Spring and Neap in Action

• The animation below shows the revolution of the moon and spring vs. neap tides.

Multiple Choice

Look at the picture and answer below.

• f

• g

• h

• j