Answer:
(a) The self inductance, L = 21.95 mH
(b) The energy stored, E = 4.84 J
(c) the time, t = 0.154 s
Explanation:
(a) Self inductance is calculated as;

where;
N is the number of turns = 1000 loops
μ is the permeability of free space = 4π x 10⁻⁷ H/m
l is the length of the inductor, = 45 cm = 0.45 m
A is the area of the inductor (given diameter = 10 cm = 0.1 m)
  
 

(b) The energy stored in the inductor when 21 A current ;

(c) time it can be turned off if the induced emf cannot exceed 3.0 V;

 
        
             
        
        
        
Answer:
Explanation:
The cannonball goes a horizontal  distance of 275 m . It travels a vertical distance of 100 m 
Time taken to cover vertical distance =  t , 
Initial velocity u = 0 
distance s = 100 m 
acceleration a = 9.8 m /s² 
s = ut + 1/2 g t²
100 = .5 x 9.8 x t²
t = 4.51 s 
During this time it travels horizontally also uniformly so 
horizontal velocity Vx = horizontal displacement / time 
= 275 / 4.51 = 60.97 m /s 
Vertical velocity Vy 
Vy = u + gt 
= 0 + 9.8 x 4.51 
= 44.2 m /s 
Resultant velocity 
V = √ ( 44.2² + 60.97² )
= √ ( 1953.64 + 3717.34 )
= 75.3 m /s 
Angle with horizontal Ф
TanФ = Vy / Vx 
= 44.2 / 60.97 
= .725
Ф = 36⁰ . 
 
        
             
        
        
        
Answer:
I’m so sorry I tried solving it but I don’t understand it can you explain the question a little bit more ty
Explanation:
 
        
             
        
        
        
Slower cooling engenders the growth of larger crystals in igneous rocks, thus, your answer should be slow cooling!
Hope this helped!
 
        
                    
             
        
        
        
I am 95 percent sure the answer in C