B is the answer, I’m really good at this subject
        
                    
             
        
        
        
Answer:
The fundamental frequency of can is 2.7 kHz.                          
Explanation:
Given that,
A typical length for the auditory canal in an adult is about 3.1 cm, l = 3.1 cm
The speed of sound is, v = 336 m/s
We need to find the fundamental frequency of the canal. For a tube open at only one end, the fundamental frequency is given by :

So, the fundamental frequency of can is 2.7 kHz. Hence, this is the required solution.
 
        
             
        
        
        
Answer:

Explanation:
 = Cambio en la longitud de la cuerda = 0.25 cm
 = Cambio en la longitud de la cuerda = 0.25 cm
T = tensión en cuerda
A = Área de la cadena = 
d = Diámetro de la cuerda = 0.2 cm
L = Longitud original de la cuerda = 1.6 m
El cambio de longitud de una cuerda viene dado por

La tensión en la cuerda es  .
.
 
        
             
        
        
        
Answer:
r = 9.92 mm
Explanation:
Given that,
Mass of oil drop, 
It acquires 2 surplus electrons, q = +2e 
Potential difference, V = 620 V
Thie potential difference is applied between the pair of horizontal metal plates the drop is in equilibrium.
We need to find the distance between the plates.
At equilibrium,
mg = qE
Since, E = V/r (r is distance between plates)

So, the distance between the plates is 9.92 mm.