This seems like an incomplete question..
We have that the most stable nuclei are the ones with the highest average binding energy. We see that Nitrogen has a mass number of 15 and that in this region of the graph average binding energy is low. Silver and Gold are along a line where there is a constant decline in average binding energy; silver has more than gold. However, we see that at the start of this decline, there is Fe 56. This region has the elements with the highest average binding energy; Nickel with a mass number of 58 is right there and thus it is the most stable nucleus out of the listed ones.
Given :
The focal length of a concave mirror is 18 cm.
To Find :
The radius of curvature of the concave mirror.
Solution :
We know,

Therefore, the radius of curvature of concave mirror is 36 cm.
Hence, this is the required solution.
Answer:
a
The radial acceleration is 
b
The horizontal Tension is 
The vertical Tension is 
Explanation:
The diagram illustrating this is shown on the first uploaded
From the question we are told that
The length of the string is 
The mass of the bob is 
The angle made by the string is 
The centripetal force acting on the bob is mathematically represented as

Now From the diagram we see that this force is equivalent to
where T is the tension on the rope and v is the linear velocity
So

Now the downward normal force acting on the bob is mathematically represented as

So

=> 
=> 
The centripetal acceleration which the same as the radial acceleration of the bob is mathematically represented as

=> 
substituting values


The horizontal component is mathematically represented as

substituting value

The vertical component of tension is

substituting value

The vector representation of the T in term is of the tension on the horizontal and the tension on the vertical is

substituting value
![T = [(0.3294) i + (3.3712)j ] \ N](https://tex.z-dn.net/?f=T%20%20%3D%20%5B%280.3294%29%20i%20%20%2B%20%283.3712%29j%20%5D%20%5C%20%20N)
One does not simply should you do you should