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Tsunami! On December \(26,2004,\) a great earthquake occurred off the coast of Sumatra and triggered immense waves (tsunami) that killed more than 200,000 people. Satellites observing these waves from space measured \(800 \mathrm{~km}\) from one wave crest to the next and a period between waves of 1.0 hour. What was the speed of these waves in \(\mathrm{m} / \mathrm{s}\) and in \(\mathrm{km} / \mathrm{h}\) ? Does your answer help you understand why the waves caused such devastation?

Short Answer

Expert verified
The speed of the tsunami waves was about \(222.22 \, m/s\) or \(800 \, km/h\).

Step by step solution

01

Convert all measures to a single unit

Before we perform the calculation, let’s convert the given distance from kilometers to meters and given time from hours to seconds, because we want the answer in meters per second. So, \(800 km = 800,000 m\) and \(1 hour = 3600 s\).
02

Calculate Wave Speed in m/s

We use the formula for wave speed which is distance divided by time. Therefore, wave speed = distance/time = \(800,000 m / 3600 s\). This calculation gives the wave speed as approximately \(222.22 m/s\).
03

Convert the speed to km/h

To get the speed in \(\mathrm{km} / \mathrm{h}\), we need to convert \(222.22 \, m/s\) to \(\mathrm{km} / \mathrm{h}\). We know that \(1 m/s = 3.6 \, km/h\). So, \(222.22 m/s = 222.22 * 3.6 \, km/h\). The speed of the wave is therefore approximately \(800 \, km/h\).
04

Analyze the Result

A speed of \(800 \, km/h\) is extremely fast - about the cruising speed of a jet airplane. This speed helps explain the devastating effect of the tsunami. It moved so quickly that people had little time to react or escape.

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Key Concepts

These are the key concepts you need to understand to accurately answer the question.

Units Conversion
Converting units is a crucial step in solving problems like tsunami wave calculations because it ensures consistency across all measurements. For instance, when you're asked to find the speed of tsunami waves in meters per second (m/s), calculations become easier if all inputs are in compatible units.

1. **Distance Conversion**: The problem states the distance between waves is 800 km. To convert kilometers to meters, remember that 1 kilometer equals 1,000 meters. Therefore, multiply 800 by 1,000 to get 800,000 meters. This conversion ensures the distance used in calculations is consistent with the desired speed units of m/s.

2. **Time Conversion**: Similarly, converting time from hours to seconds retains consistency with the standard unit for time in speed calculations. Since 1 hour equals 3,600 seconds, the given 1 hour is converted to 3,600 seconds.

Using consistent units allows for accurate calculation and clearer understanding of the tsunami's dynamics. Converting units correctly is essential in all scientific and mathematical calculations.
Wave Speed Formula
Wave speed is a fundamental concept that helps us understand how fast a wave travels through a medium. The wave speed formula is:
\[ \text{Wave Speed} = \frac{\text{Distance}}{\text{Time}} \]
This formula calculates how quickly the wave's energy propagates from one point to another. Let's apply it to the tsunami scenario.

By substituting the numerical values, the distance is 800,000 meters and the time is 3,600 seconds. So, the wave speed equals:
\[ \text{Wave Speed} = \frac{800,000 \text{ meters}}{3,600 \text{ seconds}} \approx 222.22 \text{ m/s} \]
This results in a calculated tsunami wave speed of approximately 222.22 m/s. Utilizing this formula gives insight into how quickly waves move, crucial in understanding the tsunami's rapid onset.
Impact Analysis
Understanding the impact of tsunami waves involves not just calculating speed, but also interpreting what this speed means in real-life situations. At a speed of 800 km/h, comparable to that of a commercial jet, the tsunami can reach coastlines in mere minutes, offering little time for evacuation plans.

Here's why these waves are so destructive:
  • **Sudden Arrival**: The incredibly fast travel speed means waves can strike without warning, reducing chances to alert and relocate people.
  • **Immense Energy**: At such high speeds, even relatively small waves can carry significant energy, capable of demolishing structures and landscapes.
  • **Widespread Effect**: Large areas are impacted simultaneously, stretching rescue and relief resources thin.
Analyzing the speed also aids in designing better early warning systems. Understanding how fast and far these forces travel can guide improvements in infrastructure and planning, reducing future casualties.

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Most popular questions from this chapter

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