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Natural Disasters and Safety - Understanding Earthquakes and Storms

Grade 5CBSE

Review the key concepts, formulae, and examples before starting your quiz.

🔑Concepts

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An earthquake is a sudden shaking of the Earth's surface caused by the movement of TectonicTectonic plates in the Earth's crust.

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The FocusFocus is the point inside the Earth where the earthquake starts, while the EpicenterEpicenter is the point on the surface directly above the FocusFocus.

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Earthquake intensity is measured using an instrument called a SeismographSeismograph, and the magnitude is expressed on the RichterRichter scale (ranging from 11 to 1010).

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Cyclones or storms are caused by high-speed winds blowing around a central area of very LowLow atmospheric pressure.

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Tsunamis are giant sea waves caused by underwater earthquakes or volcanic eruptions, reaching heights of over 3030 meters.

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During an earthquake, the primary safety rule is: DropDrop, CoverCover, and Hold onHold\ on.

📐Formulae

P=FAP = \frac{F}{A}

Speed=DistanceTimeSpeed = \frac{Distance}{Time}

Magnitude∝log⁡(Energy)Magnitude \propto \log(Energy)

💡Examples

Problem 1:

During a storm, if the wind exerts a force of 500500 NN over a window with an area of 22 m2m^2, calculate the pressure PP exerted on the window.

Solution:

P=500 N2 m2=250 N/m2P = \frac{500\ N}{2\ m^2} = 250\ N/m^2 (or 250 Pa250\ Pa)

Explanation:

Pressure is defined as the force applied per unit area. In storms, high wind speeds increase the force FF on structures, leading to higher pressure PP.

Problem 2:

Identify the difference in energy between an earthquake of magnitude 44 and magnitude 55 on the RichterRichter scale.

Solution:

An increase of 11 point on the RichterRichter scale represents 1010 times the amplitude and approximately 3232 times more energy.

Explanation:

The RichterRichter scale is logarithmic. Therefore, an earthquake of magnitude 55 is significantly more destructive than one of magnitude 44.

Problem 3:

A cyclone is moving towards the coast at a speed of 2020 km/hkm/h. If the coast is 100100 kmkm away, how much time do the authorities have to evacuate the area?

Solution:

Time=DistanceSpeed=100 km20 km/h=5 hoursTime = \frac{Distance}{Speed} = \frac{100\ km}{20\ km/h} = 5\ hours

Explanation:

Using the basic speed formula, we can calculate the time available for disaster management and safety measures.

Understanding Earthquakes and Storms Revision - Class 5 Science CBSE