Explanation:
Formula which holds true for a leans with radii  and
 and  and index refraction n is given as follows.
 and index refraction n is given as follows.
           ![\frac{1}{f} = (n - 1) [\frac{1}{R_{1}} - \frac{1}{R_{2}}]](https://tex.z-dn.net/?f=%5Cfrac%7B1%7D%7Bf%7D%20%3D%20%28n%20-%201%29%20%5B%5Cfrac%7B1%7D%7BR_%7B1%7D%7D%20-%20%5Cfrac%7B1%7D%7BR_%7B2%7D%7D%5D) 
Since, the lens is immersed in liquid with index of refraction  . Therefore, focal length obeys the following.
. Therefore, focal length obeys the following.  
             ![\frac{1}{f_{1}} = \frac{n - n_{1}}{n_{1}} [\frac{1}{R_{1}} - \frac{1}{R_{2}}]](https://tex.z-dn.net/?f=%5Cfrac%7B1%7D%7Bf_%7B1%7D%7D%20%3D%20%5Cfrac%7Bn%20-%20n_%7B1%7D%7D%7Bn_%7B1%7D%7D%20%5B%5Cfrac%7B1%7D%7BR_%7B1%7D%7D%20-%20%5Cfrac%7B1%7D%7BR_%7B2%7D%7D%5D) 
  
              ![\frac{1}{f(n - 1)} = [\frac{1}{R_{1}} - \frac{1}{R_{2}}]](https://tex.z-dn.net/?f=%5Cfrac%7B1%7D%7Bf%28n%20-%201%29%7D%20%3D%20%5B%5Cfrac%7B1%7D%7BR_%7B1%7D%7D%20-%20%5Cfrac%7B1%7D%7BR_%7B2%7D%7D%5D) 
and,        
or,           
                
                           = 32.4 cm
Using thin lens equation, we will find the focal length as follows.
              
Hence, image distance can be calculated as follows.
         
 
               
              
                        = 47.9 cm
Therefore, we can conclude that the focal length of the lens in water is 47.9 cm.
 
        
             
        
        
        
Answer:
C)T
Explanation:
The period of a mass-spring system is:

As can be seen, the period of this simple harmonic motion, does not depend at all on the gravitational acceleration (g), neither the mass nor the spring constant depends on this value.
 
        
             
        
        
        
Answer:
hi mate,
interesting question, first of all the pressure is determined by using the following formula:
Pg = p * G * h  
where p is the density of the liquid, G is the gravity and h is the height difference, in you case you have:
p = 1015 kg/m3
G = 9.8m/s2
h = 0.085 m  
insert these values into the equation above:
Pg = 1015 kg/m3 * 9.8m/s2 * 0.085 m = 849.81 kg·m-1·s-2 or 849.81 pascal
hope it helps, :-)
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