a stone is dropped into a well from the open mouth of the well the water level is at a depth of 25m the dound of splash is heard after 2.31s from its release the speed of stone in air inside the well is (g=10m/s^2)

Question

a stone is dropped into  a well from the open mouth of the well the water level is at a depth of 25m  the dound of splash is heard after 2.31s from its release the speed of stone in air inside the well is (g=10m/s^2)

stormfire1 · Answer

What is the question asking you to solve?

anonymous · Answer

the speed of stone

anonymous · Answer

the answer is 357m/s

stormfire1 · Answer

Let me find my calculator...

anonymous · Answer

we have to find  the speed of stone in air inside the well

stormfire1 · Answer

Well, it's impossible to drop the ball, have it fall 25m  for 2.31s with g = 10 m/s^2 and have it reach 357 m/s!

stormfire1 · Answer

Unless it's not being "dropped"....but thrown down instead

anonymous · Answer

we have to find  the speed of stone in air inside the well  plzz read this

anonymous · Answer

Did you try what @rs32623 from http://openstudy.com/study#/updates/4fb070fce4b059b524fcab29 says...

stormfire1 · Answer

First, please don't post the same question twice.  There's no point in doing that and it just confuses things when people aren't seeing each other's posts.

Second, think about the question you're asking.  If you *drop* a stone (V=0 m/s initially) and it falls with an acceleration of 10 m/s, it's not going to reach 357 m/s in only 2.31s...it will reach 23.1 m/s (acceleration * time).

Are you sure the question's wording was correctly posted here?

anonymous · Answer

yes the question is correct

anonymous · Answer

157 look the question is correct

anonymous · Answer

it's a typo...they must mean the speed of SOUND in air is...

anonymous · Answer

otherwise the time the splash is heard is irrelevant

anonymous · Answer

and of course the answers are ridiculous as stormfire1 pointed out

anonymous · Answer

the time the splash is heard  is 2.31s it is there in ques

stormfire1 · Answer

It has to be the speed of sound in the air...that's what I was thinking.

anonymous · Answer

i think this is correct they must mean the speed of SOUND in air is

anonymous · Answer

@eseidl  is right. There is a typo in the question.

Secondly.  It is easy @shameer1 .   Why don't you show what you have tried to solve this problem ??

anonymous · Answer

yep.  So we need the time it takes the stone to fall and hit the water.  Then we subtract this from the total time until the sound is heard.  2.31-t.  This is the time it takes the sound to travel 25m in air.  From this you get the speed of sound in air.

ujjwal · Answer

and if they are trying to find speed of sound, it comes out to be 338.14 m/s ... which doesn't match with any options...

anonymous · Answer

yeah I get 338.14m/s as well

anonymous · Answer

can someone show the step plz

anonymous · Answer

Yes I also get 337.83 /s

anonymous · Answer

*m/s

anonymous · Answer

maybe we need to take air resistance into account...lol

ujjwal · Answer

haha..  but sound has nothing to do with air resistance...

anonymous · Answer

yeah but it would affect the time, t,  it takes for the stone to fall and thus 2.31-t and thus our answer

ujjwal · Answer

yeah, go on find air resistance..

anonymous · Answer

ok

stormfire1 · Answer

@shameer:
$$h = \frac{1}{2}g t^2=25m$$$$t=2.2361s$$$$2.31s-2.2361=0.074s$$$$\frac{25m}{0.074s}=~338 m/s$$

anonymous · Answer

338.................. the ans should be 357

anonymous · Answer

@eseidl , if it is air resistance, then it becomes fluid mechanics question.  In that case
|dw:1336973725336:dw|

rho--->density
v--->volume
g--->10m/s