Answer:
B. When the racket hits the tennis ball with a force, the tennis ball applies an equal but opposite force to the racket.
Explanation:
According to the Newton's third law of motion every action has equal and opposite reaction. So, when the force is applied by the racket on the ball then the ball also applies an equal intensity of force in the opposite direction on the racket. It is just that the the force on the racket is absorbed by the player holding it.
 
        
             
        
        
        
Answer:
a   
b   
 
Explanation:
Generally the force constant is mathematically represented as 
        
substituting values given in the question 
=>   
=>   
Generally the workdone  in stretching the spring 3.5 m is mathematically represented as 
        
=>     
=>    
Generally the workdone  in compressing the spring 2.5 m is mathematically represented as
          
 
=>       
 
=>        
 
 
        
             
        
        
        
That's the description of the SOLID phase of matter.
        
             
        
        
        
One thing I think we must put in the capsule is our pictures. Very necessary, so that other inhabitants would see how we look like.