145 Grams!
It asks for the “Total Mass” basically asking to add, If you add 20 to 125, you get 145! Correct me if im wrong
Answer:
Mutual inductance, 
Explanation:
(a) A toroidal solenoid with mean radius r and cross-sectional area A is wound uniformly with N₁ turns. A second thyroidal solenoid with N₂ turns is wound uniformly on top of the first, so that the two solenoids have the same cross-sectional area and mean radius.
Mutual inductance is given by :

(b) It is given that,


Radius, r = 10.6 cm = 0.106 m
Area of toroid, 
Mutual inductance, 

or

So, the value of mutual inductance of the toroidal solenoid is
. Hence, this is the required solution.
The representation of this problem is shown in Figure 1. So our goal is to find the vector

. From the figure we know that:

From geometry, we know that:

Then using
vector decomposition into components:

Therefore:

So if you want to find out <span>
how far are you from your starting point you need to know the magnitude of the vector

, that is:
</span>

Finally, let's find the <span>
compass direction of a line connecting your starting point to your final position. What we are looking for here is an angle that is shown in Figure 2 which is an angle defined with respect to the positive x-axis. Therefore:
</span>