Question

The radius of circular field of village Amadpur is 280 meter. Chaitali wants to go round thefield by walking with speed 5.5 km/hour, let us calculate how long will be taken by Chaitalito complete one revolution.​

Answer 1

$\sf\large\underline{Given:}$

$\tt{\implies Radius\:of\: field=280}$

$\sf\large\underline{To\: Find:}$

• Time taken by Chaitali to complete one revolution of the field]

$\sf\large\underline{Solution:}$

• At first we have to calculate the perimeter of the field than convert speed in ms than calculate time taken by Chaitali]

$\sf\large\underline{Formula\:used:}$

$\tt{\implies Perimeter\:of\: circle=2\pi\:r}$

$\tt{\implies Perimeter\:_{(circle)}=2\times\:\dfrac{22}{7}\times\:280}$

$\tt{\implies Perimeter\:_{(circle)}=2\times\:22\times\:40}$

$\tt{\implies Perimeter\:_{(circle)}=1760m}$

• Convert the speed in m/s here to convert speed , we have multiple by 5/18]

$\tt{\implies Speed=5.5\times\dfrac{5}{18}}$

$\tt{\implies Speed=\dfrac{55}{36}m/s}$

• Now, calculate total time taken by Chaitali here Note one thing here , perimeter of field is here total distance covered by Chaitali]

$\tt{\implies Time=\dfrac{Distance}{Speed}}$

$\tt{\implies Time=1760\div\dfrac{55}{18}}$

$\tt{\implies Time=1760\times\dfrac{36}{55}}$

$\tt{\implies Time=32\times\:36}$

$\tt{\implies Time=1152\: second}$

Hence,

• Time taken by Chaitali to complete one revolution of the field is 1152 second]

Answer 2

Answer

Given :

• The radius of a village amadpur is 280 meter.
• A girl named chaitali wants to go round the field by walking.
• The speed of chaitali is 5.5 km/h.

Find :

• The time taken by chaitali to complete one revolution around the village Amadpur.

Step by Step Explanation :

First of all, we need to find the circumference of the village Amadpur . We already have the radius of the village that is 280 meter.

$\dag$ Formula for circumference of Circle

$\boxed{\bold {2 × \pi × radius}}$

The circumference of the village :

$\implies$${\bold {2 × \pi × radius}}$

$\implies$${\bold {2 × \dfrac {22}{7} × 280}}$

$\implies$${\bold {2 × 22 × 40}}$

$\implies$${\bold {44 × 40}}$

$\implies$${\bold {1760}}$

The circumference of the village is 1760 m .

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Now,

Let us find the time taken by Chaitali to Cover one revolution around the village.

• Speed of chaitali = 5.5 km/h

Convert the speed km/h to m/s

= 5.5 × $\dfrac {5}{18}$

= $\dfrac {55}{18}$

$\dag$ Formula of Time :

$\boxed {\bold {Time = \dfrac {Distance}{Speed}}}$

The time taken to cover one revolution :

$\implies$${\bold {Time = \dfrac {Distance}{Speed}}}$

$\implies$${\bold {Time = 1760 ÷ {\dfrac {55}{18}}}}$

$\implies$${\bold {Time =1760 ×\dfrac {18}{55}}}$

$\implies$${\bold {Time =32 × 18}}$

$\implies$${\bold {Time =576}}$

•°• Thus, chaitali will take 576 seconds to cover one revolution around her village Amadpur.

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