Question

two persons p and q are standing at a distance of 100 M from a high wall as shown in the figure when we give the clap the time interval between two direct and reflected sound hereby Q is 0.2 seconds if the speed of the sound is 340 metre per second then the distance between the P and Q is what ​

Answer 1

Answer:

the distance between the P and Q is 72.25 m

Explanation:

Let say Distance Between P & Q  = d  m

Distance of Wall from P & Q = 100 m

Let say Distance of reflection point on wall from P & Q

= a  &  b  m

Reflection at 90°  so a & b are perpependicular

=> a² + b² = d²

Also Area of  triangle

= (1/2) a * b = (1/2) * d * 100

=> ab  = 100d

Difference between reflected and Direct sound = 0.2 sec

Distance covered in 0.2 sec = 340 * 0.2 = 68 m

=> a + b =  d + 68

Squaring both sides

=> a² + b² + 2ab  = d² + 68² + 136d

using a² + b² = d²   & ab = 100d

=> d² + 200d = d² + 68² + 136d

=> 64d = 68²

=> 4d = 17²

=> d = 289/4

=> d = 72.25 m

the distance between the P and Q is 72.25 m