Question

A stone is dropped from the top of the tower 500m high into a pond of water at the base of the tower. When is the splash heard at the top? Given, g = 10 m/s sq. and speed of sound = 340 m/s.

I don't get this concept. Please explain.

Answer 1

thats very simple bro
       given height,s=500m
                g=10
       speed of sound =340
 on analysing we get that  we have to find time period
first analyze the data and apply different formulas for it then see which formula suits the best.
         the formula that should be used here is
                                   s=ut+1/2at2
                          u=0,
                  500=0+1/2x10xtxt
we get t=10 sec
 now the time for the resound=500/340=1.47 sec
 total time=10+1.47=11.47 sec

Answer 2

s = 500 m = distance to travel - for the stone
g = 10 m/sec/sec,        initial velocity of stone  u = 0
equation of the dynamics of stone :
     s = u t + 1/2 g t^2
       500 = 0  + 1/2 * 10 * t^2

  t =  10 sec

Immediately after touching the water, in a fraction of second, there is a sound wave produced on the surface of water - splashing of water.

time for sound to reach the top = distance to travel / speed = 
                 500 meter / 340 m/sec  = 25/17 sec

total time = 10 sec + 25/17 sec