Science Section 4 Tides

​ (a)   are daily changes in the level of ocean water. They are influenced by the ​ (b)   . ​ (c)   is the difference between high and low tides. The role of the ​ (d)   was first discovered over 2000 years ago by ​ (e)   , but he could not explain it.

• Tides
• moon and sun
• Tidal range
• moon
• Pytheas

In 1867, Sir Isaac Newton's theories on ​ (a)   helped explain tides. The gravity of the ​ (b)   pulls on Earth. ​ (c)   is affected because it is easier to move than ​ (d)   The​ (e)   also has a gravitational pull on Earth, but it is much less than the moon because it is so far away.

• gravity
• planetary motion
• moon
• Water
• land.
• Sun

Match the following

• High Tides

• Occur every 14 days during the first and third quarter moon phases and have the smallest daily tidal range.

• New Moon

• The moon phase that occurs when the moon is directly between the Earth and sun.

• Spring Tides

• The bulges that form in the oceans because of the moon's pull.

• Full Moon

• The Moon Phase that occurs when the moon is on the opposite side of Earth from the sun.

• Neap Tides

• Occur every 14 days during new and full moons, have the largest daily tidal range.

In areas between high tides, ​ (a)   form. In these areas, the water level is ​ (b)   than the average sea level. This happens because the water is pulled toward the ​ (c)   areas.

• low tides
• lower
• high tide
• higher

The moon's gravitational pull on Earth ​ (a)   with the distance from the moon. The part of the Earth that ​ (b)   the moon is pulled with the greatest force. A place that is facing the moon takes ​ (c)   to face the moon again.​ Therefore high and low tides at that place happen about ​ (d)   each day.

• decreases
• increases
• faces
• 24 hours and 50 minutes
• 50 minutes later
• 50 minutes earlier

The movement of Earth around its axis that causes day and night. Takes about 24 hours to complete.

• Rotation

• Revolution

• Orbit

• Ellipse

The movement of Earth around the Sun. Takes about 365 days to complete.

• Rotation

• Revolution

• Elliptical

• Tilt

How much time passes between a spring tide and a neap tide?

• 14 days

• 7 days

• 1 month

• 24 hours

Choose which would have the greatest tidal range.

• High Tide

• Low Tide

• Spring Tide

• Neap Tide

Neap tides occur because...

• The Earth is closer to the moon

• The Earth is farther away from the moon

• The gravity of the sun and moon partly cancel out.

• The gravity of the sun and moon work together.