Question

Vijay has dropped a stone from the top of a tower of 125 m. high into a pond which
is at base of the tower. When the splash will be heard at top?
(g = 10 ms? and speed of sound is 340 ms-1)
(A) 5 s
(B) 5.63 s
(C) 5.36 s
(D) 4.64 s​

Answer 1

Answer:

Time = 5 seconds

Explanation:

Height = 125 m

g = 10 m/s²

From equations of motion,

s = ut + 1/2 × g × t²

125 = 1/2 × g × t²

125 = 1/2 × 10 × t²

125 = 5t²

t² = 125/5

t² = 25

t = 5s

Answer 2

Answer:

(C) 5.36s

Explanation:

Height of tower, S= 125m

U=0

g=10 m/s/s

So,

S= ut +1/2at^2

125=1/2* 10t^2

250/10= t*t

25= t^2

5 =t

So the time taken to fall in the pond is 5 second.

Then

Speed of sound is 340 m/s

Distance =125m

t=d/s

t=125/340

t=0.36 s

Hence Time taken to hear splash is (5+0.36)s=5.36 second