Explanation:
Rhythm, Harmony, Timbre, Dynamics, Texture, and Form
Answer:
Explanation:
Given
Distance between two loud speakers 
Distance of person from one speaker 
Distance of person from second speaker 
Path difference between the waves is given by

for destructive interference m=0 I.e.




frequency is given by

where 

For next frequency which will cause destructive interference is
i.e.
and 


frequency corresponding to this is

for 


Frequency corresponding to this wavelength

Since you didn't provide how tall the Monument was, I took the liberty to find it and it is 555 feet tall. So to convert to meters we must divide 555 by 3.28 or multiply it by 0.3048 (this is the method I used).
555 x 0.3048 = 169.164 meters
Kinetic Energy = 1/2 * mv²
Kinetic Energy = 14 J, v = 2.3 m/s , m = ?
14 = 1/2 * m* 2.3²
14 = 0.5*m*2.3*2.3
m = 14 / (0.5*2.3*2.3)
m = 5.29 kg.
Mass = 5.29 kg.