Answer:

Explanation:
From the question we are told that:
Frictional force 
Coefficient of kinetic friction 
Generally the equation for Normal for is mathematically given by
  
Therefore
  
  
 
        
             
        
        
        
A 500 g ball swings in a vertical circle at the end of a 1.4-m-long string. when the ball is at the bottom of the circle, the tension in the string is 18 n.
 
        
             
        
        
        
 As per above given data
initial velocity = 19.3 km/s
final velocity = - 18.8 km/s
now in order to find the change in velocity




Part b)
Now we need to find acceleration
acceleration is given by formula

given that


now the acceleration is given as


so above is the acceleration
 
        
             
        
        
        
bonsoir, je peux vous aider avec les maths laissez-moi comprendre merci
 
        
             
        
        
        
Hydrogen has one proton whereas helium has two protons in its nucleus.
<h3>How hydrogen and helium atoms different from one another?</h3>
Atoms of hydrogen have a single proton in their nucleus and a single electron in the lowest energy level while on the other hand, Helium atoms have two protons in the nucleus  and two electrons in the lowest energy level. In this way, we can say that the atomic number of hydrogen is 1 whereas the atomic number of helium is 2 because of the presence of two protons. Hydrogen atom has no neutron while on the other hand, the helium atom has one neutron in its nucleus.
So we can conclude that Hydrogen has one proton whereas helium has two protons in its nucleus.
Learn more about atom here: brainly.com/question/6258301
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