I am 11 year old and u just needed to login in so I can't answer ur questions
        
             
        
        
        
An important aspect of fission reactions is that they produce free neutrons,  which causes chain reactions.
 
        
                    
             
        
        
        
For the first question, you got them right, for the two you left blank, initial(beginning) velocity: 2 m/s the final velocity is: 12 m/s
        
             
        
        
        
Ahhh... hello! I’ve done a science experiment that has asked this sort of question. Not as easy as it sounds... I know. I’ll tell you what I learned from that experiment. The answer will depend on the materials the ball is made of and then also your drop length. After these two things are determined, you can get a pretty close time and measurement. I hope this information helps. Have a great night! 
~Brooke❤️
        
             
        
        
        
The friction force is given by:

Where μ is the coefficient of friction (static or kinetic) and 

 is the normal force.  So we say the friction force is directly proportional to the normal force with a constant of proportionality equal to the coefficient of friction.