The answer is The Doppler Effect.  It is named after the Austrian physicist Christian Doppler, who described the phenomenon in 1842.
 
        
             
        
        
        
Answer:
The waiting room became the conditioned stimulus. 
Explanation:
Conditioned stimulus is the reflexive behaviors or the learned behavior.
This stimulus may be defined as a neutral stimulus that with some time and some training will evoke a response by continuously being associated with any other natural occurring stimulus. 
 
        
             
        
        
        
<u>Answer:</u>
<em>A constant is something whose value cannot be changed and is used for comparison purpose. </em>
<u>Explanation:</u>
The controlled variable is a type of variable whose value is kept constant during the experiment to get the desired or expected result. The difference between constant and a control variable is that the constant can never be changed. 
However, the value of control variable can be changed but is kept constant with a purpose in an experiment to get the data. The controlled variable in a battery can be the multi meter that should be used for all the batteries.
 
        
             
        
        
        
Heart is made up of Cardiac muscle
        
                    
             
        
        
        
Answer: increased variation in the shades of red because the cardinals try different ways to impress the females
Explanation: If different colors of coolors are mixed together, then its likely that throught time, new colors will develop. Good Luck!!