Answer:
f = 632 Hz
Explanation:
As we know that for destructive interference the path difference from two loud speakers must be equal to the odd multiple of half of the wavelength
here we know that

given that path difference from two loud speakers is given as


now we know that it will have fourth lowest frequency at which destructive interference will occurs
so here we have



now for frequency we know that


 
        
             
        
        
        
Answer:
M= F^n / a+g
Explanation:
This shows correctly Newton’s second law, where sum of forces is divided by mass is equal to acceleration. Also mass can’t be negative so F^n is positive.
 
        
                    
             
        
        
        
Answer:
Explanation:
If we assume there is a sharp boundary between the two masses of air, there will be a refraction. The refractive index of each medium will depend on the relative speeds of light.
n = c / v
If light travels faster in warmer air, it will have a lower refractive index
nh < nc
Snell's law of refraction relates angles of incidence and refracted with the indexes of refraction:
n1 * sin(θ1) = n2 * sin(θ2)
sin(θ2) = sin(θ1) * n1/n2
If blue light from the sky passing through the hot air will cross to the cold air, then 
n1 = nh
n2 = nc
Then:
n1 < n2
So:
n1/n2 < 1
The refracted light will come into the cold air at angle θ2 wich will be smaller than θ1, so the light is bent upwards, creating the appearance of water in the distance, which is actually a mirror image of the sky.
 
        
             
        
        
        
Answer:
Plasma, Supersolid, Superfluid
Explanation:
I don't know if this is what you are looking for, but I have no idea what these even are.
 
        
             
        
        
        
Answer:
50N
Explanation:
Force (N) = mass (kg) × acceleration (m/s²)
0.25kg times 200m/s² = 50N