Answer:
43.2 N
Explanation:
= Wavelength = 0.75 m
f = Frequency = 40 Hz
m = Mass of string = 0.12 kg
L = Length of string = 2.5 m
= Linear density = 
Velocity of wave is given by
The tension in string is given by
The tension in the string is 43.2 N
Use the inverse square law, thus if you move a distance of 3m away, the sound intensity decrease by 1/3^2= 1/9
Density depends on mass and volume so option D is correct answer. Hope this helps!
The second one since you’re changing the soil up by adding different fertilisers. This will be you’re independent variable. And you’re dependent variable is your result = the plant height .
Hope this helps :)
