# Alex throws a 5kg stone down a well with an intial velocity of 5.4 m/s. The stone falls for 2.5 seconds before he hears it hit the bottom.?

What is the stone's acceleration?

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- JimLv 72 months ago
acceleration is assumed to be standard gravity of -9.80665 m/s²

If so, we can find the height

y(t) = ½at² + v₀t + y₀ is the basic formula you need to know.

0 = ½ g (2.5²) + 5.4(2.5) + y₀ and solve for initial height

y₀ = 44. m (rounded to 2 sigfigs)

Source(s): Notice mass of stone is ignored. - billrussell42Lv 72 months ago
the question is contradictory. is the 2.5 seconds time of fall, when it hits the bottom or is it the time the sound is heard, they are different, as it takes time for the sound to travel from the bottom to the top.

but the answer is 9.8 m/s²

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- 2 months ago
What is the stone's acceleration? Gravity. The rock will accelerate at about 9.8 m/s every second.

- SlowfingerLv 62 months ago
This is trick question.

Stone's acceleration remains g=9.81 m/s^2 regardless of mass or initial velocity.

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