Question

a stone is dropped into a lake from a tower 500m high.the sound of splash will be heard by the man approx. after (a)11.5sec (b)10 sec (c)21 sec (d)14 sec

Answer 1

We know that

s = ut +1 /2 at²

here

u = 0
a = g

s = 500m

so putting value in above equation

we get

t = 10s

Now
Velocity of sound in air 332m/s

time of sound travel = (t1 - 10)sec

Distance= sound ×time
500 = 332 × (t1 -10)

t1 = 11.5 sec

Answer 2

11.5 sec is correct answer