Answer:it helps get everyone in the same page 
Explanation:
This is important so everyone knows what they should be doing
 
        
             
        
        
        
Anything less dense than water will float, like oil. Anything more dense than water will sink, like rock.
        
             
        
        
        
Another name for these two words is "constant" and you want to have a "constant", because you want something to compare your experimental group to, to see whether data had changed or not. So you have placebos or a double- blind to compare your experimental group to it and also so you know you don't have a bias or anything in the study.
        
             
        
        
        
Answer:
e.26m/s
Explanation:
Vf=Vi+at      (1)
Vf=9j+(2i-4j)t
 X= X₀+at
now, in the i direction
15=O+2t or t=7.5 when x position is 15
Lets put that into the (1) equation, solve for Vf.
  Vf=9j+(2i-4j)7.5
Vf= 15i - 21j
Speed=  
 
Vf= 25.8 m/s