Answer:Technician A
Explanation:
Technician A statement is correct as  
The battery is required to start the vehicle which, in effect, rotates the alternator at sufficient speed to keep the battery charged. This means if the battery is low it is not possible to start the vehicle and thus we are unable to test the alternator.  
That is the battery is pre-requisite to test the alternator. So the battery must be at least a 75 % charge to test the alternator.
 
        
             
        
        
        
Answer:
The force is  
Explanation:
From the question we are told that
     The  mass of the block is  
      The  coefficient of  static friction is  
      The coefficient of kinetic friction is  
The  normal force acting on the block is   
       
substituting values 
      
      
Given that the force we are to find is the force required to get the block to start moving then the force acting against this force is the static frictional force which is mathematically evaluated as 
         
substituting values
         
         
Now for this  block to move the force require is  equal to  i.e
 i.e 
        
=>    
         
     
 
        
             
        
        
        
the International System of Units, the fundamental units are: The meter (symbol: m), used to measure length. The kilogram (symbol: kg), used to measure mass. The second (symbol: s), used to measure time. The ampere (symbol: A), used to measure electric current.
 
        
             
        
        
        
Answer:
K.E = 30,000 J
Explanation:
Given,
The potential energy of the roller coaster car, P.E = 40000 J
The kinetic energy at height h/4, K.E = ?
According to the law of conservation of energy, the total energy of the system is conserved.
At height 'h', the total energy is,
                                     P.E = mgh
                                      K.E = 0
At height 'h/4', the total energy is
                                      P.E + K.E = mgh
                                      P.E = mgh/4
                                      K.E = 1/2 mv²
Therefore,
                                    mgh/4 + 1/2 mv² = mgh
                                     gh/4 + v²/2 = gh
Hence, 
                                       v² = 3gh/2
Substituting in the K.E equation
                                K.E = 1/2 mv²
                                       = 1/2 m (3gh/2)
                                        = 3/4 mgh
                                         = 3/4 x 40000
                                          = 30000 J
Hence, the K.E of the roller coaster car is, K.E = 30000 J