Answer:
B
Explanation:
this is because the neutrons do not have a charge, the things that have charge in an atom are electrons and protons. 
and in the nucleus of an atom, there are protons and neutrons so you can see that A is not the answer
if you see the periodic table, you will know that the number of electrons and protons are equal, so the charges cancel each other out, hence the charge of an atom will be neutral 
let me give you a tip which I got from my teacher, never write there is no charge in the atom, this suggests that there is no protons or electrons. 
instead, write, the it is neutral 
hope it helps if not please report it so that someone else gets to try it out 
 
        
             
        
        
        
<span>The distance between wave crests is called wavelength. It is a characteristic shared by waves of all kinds, including ocean waves and sound waves. Wavelength is measured from the highest point, or summit, of one wave's crest to the summit of the next wave's <span>crest</span></span>
<span><span>hope this helps</span></span>
 
        
             
        
        
        
<u>Answer :</u>
(a) d = 0.25 m
(b) d = 0.5 m
<u>Explanation :</u>
It is given that,
Frequency of sound waves, f = 686 Hz
Speed of sound wave at  is, v = 343 m/s
 is, v = 343 m/s
(1) Perfectly destructive interference occurs when the path difference is half integral multiple of wavelength i.e.
 ........(1)
........(1)
Velocity of sound wave is given by :




Hence, when the speakers are in phase the smallest distance between the speakers for which the interference of the sound waves is perfectly destructive is 0.25 m.
(2) For constructive interference, the path difference is integral multiple of wavelengths i.e.
 ( n = integers )
  ( n = integers )
Let n = 1 
So, 


Hence, the smallest distance between the speakers for which the interference of the sound waves is maximum constructive is 0.5 m.
 
        
                    
             
        
        
        
Answer:
Correct answer:  11. Total distance d = 200m ; 12. Vav = 3.63m/s ; 
13. Total displacement Dt = 0m ; 14. V₂(10s-15s) = 0 m/s ; 
15. V₃(15s-40s) = 4 m/s ; 16. V₁(0s-10s) = 6 m/s > V₄(40s-55s) = 2.67 m/s
Explanation:
The whole movement can be divided into four stages. 
In the first stage the subject moves 60m in a positive direction for 10s, 
in the other it is stationary for 5s, in the third it moves 100m in the opposite (negative) direction for 25s and in the fourth in the positive 40m for 15s.
11. Total distance = 60 + 0 + 100 + 40 = 200m
12. The formula for calculating the average speed (velocity) is
Vav = (S₁ + S₂ + S₃ + S₄) / (t₁ + t₂ + t₃ + t₄) 
Vav = (60 + 0 + 100 + 40)/ (10 + 5 + 25 + 15) = 200/55 = 3.63 m/s
13. The movement started from the origin and ended at the origin
Total displacement is zero meters.
14. The speed between 10s and 15s is zero, because he did not move.
15. V₃ = S₃/t₃ = 100/25 = 4 m/s
16. V₁ = S₁/t₁ = 60/10 = 6 m/s   and V₄ = S₄/t₄ = 40/15 = 2.67 m/s
V₁ > V₄
God is with you!!!
 
        
             
        
        
        
Answer:
and person at rest hears sound at a different frequency than a person moving.
Explanation: