Potential energy is energy that is found in a system, grounded on the position of objects. The Coulomb (C) is the unit of charge, and the unit of electric potential is the Volt (V), which is equivalent to (J/C) or Joule per Coulomb.So the formula for this is potential = kQ / d, plugging in the given from the questions will give us:potential = 8.99e9N·m²/C² * 1.602e-19C / 0.053e-9m = 27 V 
        
             
        
        
        
Potassium is the 19th element so it is B 
        
             
        
        
        
Answer:
The period of the pendulum is  
Explanation:
 The diagram illustrating this setup is shown on the first uploaded image 
From the question we are told that 
      The length of the rod is 
        The diameter of the ring is 
        The distance of the hole from the one end  
From the diagram we see that point A is the center of the brass ring 
  So the length from the axis of  rotation is mathematically evaluated as
            
  
           
Now the period of the pendulum is mathematically represented as
              
              
              
       
       
       
 
        
             
        
        
        
Answer:
During the experiment, alpha particles bombarded a thin piece of gold foil. The alpha particles were expected to pass easily through the gold foil. ... The discovery of the nucleus was a result of Rutherford's observation that a small percentage of the positively charged particles bombarding the metal's surface...
Explanation:
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