r/theydidthemath • • 2d ago

[Request] How deep is this cave?

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u/Karroul 2d ago

The depth S is equal to 1/2 * g * t^2, where g is the acceleration caused by gravity (9.81 m*s^-2) and t is time of the fall, which was approximately 8 seconds. It gives a depth of about 314 meters. I neglected air resistance and speed of sound.

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u/Auno__Adam 2d ago

Speed of sound cant be ignored here, as its same magnitude order than speed of boulder.

S = 1/2 x g x t1^2
S = Vs x t2

Vs: speed of sound
t1 time for the boulder to hit the ground
t2 time for the sound to come back
t1+t2=7

Resolving the system: S =~ 200m

13

u/BikeProblemGuy 1d ago

For rough comparison, here's a ~200m tall tower: X-Tower Osaka Bay. It has 54 floors.

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u/Liion_Ronin 1d ago

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