Question

49.
A stone is dropped in a well of depth 500 m and a sound is heard after 45/4 seconds. Then speed
of sound is (if g = 10 m/s):
(A) 340 m/s
(B) 350 m/s
(C) 380 m/s
(D) 400 m/s​

Answer 1

Answer:

ANSWER

here, S=−500m [ we take reference level is in initial position of stone]

u=0, a=−g =−10

use formula , S=ut+

2

1

at

2

−500=0−

2

1

×10×t

2

t

2

=100=>t=10sec

but sound is heard after 45/4=11.25sec

hence, time taken to reach 500m depth =11.25−10=1.25sec .

now speed of sound = distance/time

= 500/1.25=400m/s

Answer 2

Solution(By Examveda Team)

In Give Question,

A + B = 8 ---- (i)

A + C =13 -----(ii)

B + D = 8 ----(iii)

C - D = 6 ----(iv)

Therefore equation (i) and (iii) are equal

A + B = B + D

=> A = D

Therefore, equation (iv) can be C - A = 6 ----- (v)

Now solving equation (ii) and (v), We Get C = 9.5 and A = 3.5

Put this value of A in equation in (i) B = 4.5 and value of C in equation (iv) we get D = 3.5

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Did u get that

A = 3.5

B = 4.5

C = 9.5

D = 3.5