Question

a pebble is dropped into a well of depth h. the splash is heard after time t.if c be the velocityof sound then what is thevalue of t

Answer 1

first of all you have to find time taken by pebble to drop into the well.
= t=(v-u)÷g

secondly you have to find time taken by sound to reach to you after splashing in well.
= t = s÷c

finally you have to add both time intervals
= (v-u)÷g + s ÷c
by putting the values you can get the answer.

Answer 2

Answer:

t=2hg−−√+hv  sec

Explanation:

Say the stone takes time   t1 to travel from the top of the well to water level. The sound has to travel distance h with velocity v , say it takes time   t2 to travel from the water level to the top of the well.

Time taken by stone to cover distance h can be obtained using following equation of motion.

s=ut+12f t2  

Substituting in the above equation,

h=0×t1+12g  t21  (as initial velocity of the stone is zero.)

giving,

t1=2hg−−√  

Time taken by sound to cover distance h

t2=hv  

Total time,

t=t1+t2  

t=2hg−−√+hv  sec