Answer:
f = 8 N
Explanation:
Data provided in the question 
Radius of the pulley  = r = 0.05 m
Moment of inertia = (I) = 0.2 kg.m^{2}
Angular acceleration = ∝ = 2 rad/sec
Based on the above information 
As we know that
Torque is 


And, 
Torque is also 


So, 
We can say that 


0.05f = 0.4
f = 8 N
We simply applied the above formulas 
 
        
             
        
        
        
Find refractive index first



Now






 
        
             
        
        
        
Answer:
not clear pic...but it's definitely not A)
 
        
             
        
        
        
Answer:
31.831 Hz.
Explanation:
<u>Given:</u>
The vertical displacement of a wave is given in generalized form as 

<em>where</em>,
- A = amplitude of the displacement of the wave.
- k = wave number of the wave =  
 = wavelength of the wave. = wavelength of the wave.
- x = horizontal displacement of the wave.
 = angular frequency of the wave = = angular frequency of the wave = . .
- f = frequency of the wave.
- t = time at which the displacement is calculated.
On comparing the generalized equation with the given equation of the displacement of the wave, we get,

therefore, 

It is the required frequency of the wave.
 
        
             
        
        
        
It's a form of mechanical energy