Year 7 Science · Unit 4 · Lesson 9
Apply Worksheet
Learning Goals
Spring or neap? Complete the chain
For each Moon arrangement, decide whether you get a spring tide or a neap tide, and write it in the empty box.
Explain the pattern: when are tides biggest, and why?
Real-world context
Below is a simple tide chart for one day at an Australian beach. It shows the times of the high tides and low tides and the height of the water in metres. The Bureau of Meteorology produces charts like this for ports all around Australia, calculated from the positions of the Sun, Earth and Moon.
| Time | Tide | Height (metres) |
|---|---|---|
| 5:10 am | High tide | 1.8 |
| 11:30 am | Low tide | 0.3 |
| 5:45 pm | High tide | 1.7 |
| 11:55 pm | Low tide | 0.4 |
(a) How many high tides and how many low tides are there in this one day? Does this match what you learned about the two tidal bulges?
(b) Work out the tidal range for the morning by subtracting the low tide height from the first high tide height. Show your working.
(c) A skipper needs the deepest water to bring a boat safely into a shallow harbour. Using the chart, what time of day should the skipper aim for, and why?
1. At Broome in Western Australia the tide can rise and fall by more than 9 metres in a day. Explain why tides this large can still be predicted accurately by the Bureau of Meteorology.
2. A friend says "Spring tides only happen in the season of spring." Explain why your friend is wrong.
Wrap Up
In one sentence, what was the main idea of this lesson?