Answer:
The  fraction fraction of the final energy is stored in an initially uncharged capacitor after it has been charging for 3.0 time constants is  
       
Explanation:
From the question we are told that 
      The time  constant  
The potential across the capacitor can be mathematically represented as 
      
Where  is the voltage of the capacitor when it is fully charged
 is the voltage of the capacitor when it is fully charged 
     So   at   
 
      
      
    Generally energy stored in a capacitor is mathematically represented as
              
In this equation the energy stored is directly proportional to the the square of the potential across the capacitor 
Now  since capacitance is  constant  at   
 
         The  energy stored can be evaluated at as 
          
        
Hence the fraction of the energy stored in an initially uncharged capacitor is  
       
 
        
             
        
        
        
Since force is mass*acceleration,
F = 70kg * 9.8 m/s
 
        
             
        
        
        
Answer:
The strategy we would like you to learn has five major steps: Focus the Problem, Physics Description, Plan a Solution, Execute the Plan, and Evaluate the Solution. Let's take a detailed look at each of these steps and then do an sample problem following the strategy.