Question

$\huge\bold{\underline{\underline{{Question:}}}}$


✤ Dave Kumar is the first person verified to have completely circled the entire earth on foot which is 23,255 km, in 4 years. Let us assume he travelled in a perfect circle around the earth. Now he digs a tunnel through the centre of the earth penetrating it to other side of earth. How much approximately will it take for him to go the other side on foot? ( Assume he travels at a constant speed )

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Answer 1

Your answer is in pic.

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Answer 2

GIVEN

Dave Kumar is the first person verified to have completely circled the entire earth on foot which is 23,255 km, in 4 years.

❈ Perimeter of Earth = 23,255 km

❈ Time taken by Dave = 4 years

❈ Dave digs a tunnel through the center of the earth penetrating it to other side of earth.

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TO FIND

The time taken by Dave to reach the other side of the earth through the tunnel, by foot.

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SOLUTION

☛ Dave travelled 23255 km in 4 years.

4 years = 4 × 8760 = 35040 hours

We know,

$\boxed{\mathbf{\dag\ Distance=Speed \times Time}}$

Putting the values :-

$\sf{\implies 23255=Speed \times 35040}\\\\\boxed{\sf{\implies Speed=0.663\ km/h}}\:\:\:\:\:\: \cdots \sf{(i)}$

$\rule{150}{1.4}$

A/q,

☛ Dave travelled in a perfect circle around the earth. Therefore, the perimeter (or circumference) of the circle = 2πr = 23255 km

Taking π as 22/7 :-

$\sf{\implies 2\times \dfrac{22}{7} \times r=23255}\\\\\sf{\implies \dfrac{44}{7}r =23255 }\\\\\sf{\implies r=23255 \times \dfrac{7}{44} }\\ \\\boxed{\sf{\implies r=3699.65\ km}}$

$\rule{150}{1.4}$

Now,

Length of the tunnel = diameter of the Earth

⇒ Length of the tunnel = 2 × r

⇒ Length of the tunnel = 2 × 3699.65

⇒ Length of the tunnel = 7399.3 km

​Speed is assumed to be constant.

Time taken = Length of the tunnel/Speed

⇒Time taken = 7399.3/0.663      ...[From (i)]

⇒Time taken = 11160.33 hours

⇒Time taken = 11160.33/8760 years

⇒Time taken = 1.27 years (Approx.)

⇒Time taken = 1 year 27 months

⇒Time taken = 3 year 3 months  ...(ANSWER)

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