Answer. dry friction- <span> resists relative lateral motion of two solid surfaces in contact.</span>
        
             
        
        
        
It is 6 g/cm3 because density cannot be negative, and it is not speed in which the unit would be m/s.
        
                    
             
        
        
        
Answer:
White dwarfs are likely to be much more common. The number of stars decreases with increasing mass, and only the most massive stars are likely to complete their lives as black holes. There are many more stars of the masses appropriate for evolution to a white dwarf.
 
        
             
        
        
        
Answer:
D By looking all the way to the cosmological horizon, we can see the actual conditions that prevailed all the way back to the first instant of the Big Bang.
Explanation:
Astrophysicists are able to determine the conditions that existed in the early universe, by using instruments such as telescopes to observe and study cosmic horizons. More ideas about the early universe can be found from the thermal light present in cosmic backgrounds. 
Scientists study these details that provide an insight into the conditions that existed so many years ago. They have been able to determine that the Big Bang involved so many collisions from these observations.