A rock is held steady over a well and dropped. 4.6 seconds later, the sound of the rock hitting water is heard. Sound travels at a constant speed of 347 m/s. How deep is the well?

Question

ganeshie8 · Answer

|dw:1379541634623:dw|

ganeshie8 · Answer

say $d$ is the depth of of well

ganeshie8 · Answer

say it takes $t$ seconds for stone to hit water
so it wud take $4.6-t$ seconds for sound to travel

ganeshie8 · Answer

distance travelled by stone  :-

$\large d  = \frac{1}{2} \times  9.8 \times t^2$ ----------(1)

ganeshie8 · Answer

same  distance is travelled by sound on the way up :-

$\large d  = 347 \times (4.6-t)$ ----------(2)

ganeshie8 · Answer

two equations, two unknowns
we should be able to solve them ?

anonymous · Answer

solve for t then plug into one of the above equations correct?

anonymous · Answer

to get d

ganeshie8 · Answer

yup you can do that

ganeshie8 · Answer

after all is done, you shoudl get $d = 92.0681$

ganeshie8 · Answer

good luck !

anonymous · Answer

thank u. i got this wrong. i will learn from it

ganeshie8 · Answer

good, np :)

ganeshie8 · Answer

did u get how i wrote the equation (1)  ?

anonymous · Answer

yes i understand. u usually do not take more than one problem? is it ok if i ask u if i am stuck on sthing?

ganeshie8 · Answer

nthing like that lol, sure u can tag me...  :D