A student collects data on spring and neap tides, in feet, on four different days of the same year in Anchorage, Alaska. The graphs of her data are shown below.

Modified from image courtesy of NOAA

Based on the data given, which statement is true about the tides?
A.
September 16 and October 2 represent neap tides due to the added gravitational pull of the Moon.
B.
September 9 and 24 represent spring tides due to the added gravitational pull of the Sun.
C.
September 16 and October 2 represent spring tides due to the added gravitational pull of the Sun.
D.
September 9 and 24 represent neap tides due to the added gravitational pull of the Moon.

1 answer

To answer the question, we need to understand the differences between spring tides and neap tides:

  • Spring Tides occur when the Earth, the Moon, and the Sun are aligned, resulting in higher high tides and lower low tides. This usually happens during the full moon and new moon phases.

  • Neap Tides occur when the Moon is at a right angle to the Earth-Sun line, resulting in lower high tides and higher low tides. This typically occurs during the first and third quarters of the moon.

Given that the student has collected data on four different days, we would expect to see patterns in the tide heights indicating which days had spring tides and which had neap tides based on the gravitational effects of the Moon and Sun.

From the answer choices, we can analyze them:

A. September 16 and October 2 represent neap tides due to the added gravitational pull of the Moon.

  • If these dates correspond to lower high tides and higher low tides, then this statement could be true.

B. September 9 and 24 represent spring tides due to the added gravitational pull of the Sun.

  • If these dates correspond to higher high tides and lower low tides, then this statement could be true.

C. September 16 and October 2 represent spring tides due to the added gravitational pull of the Sun.

  • If these dates correspond to higher tides, this could potentially be true.

D. September 9 and 24 represent neap tides due to the added gravitational pull of the Moon.

  • If these dates correspond to lower tides, then this statement could be true.

Without the graphs, we cannot definitively determine which tides correspond to which dates. However, if September 9 and 24 showed higher tide levels, then statement B would be correct. Conversely, if September 16 and October 2 had higher tides, they would support statement C.

In the absence of graph data, the correct answer cannot be determined from the provided statements alone. It is essential to refer to the tide data to see highs and lows clearly for proper selection.