Answer:
Hi 
before I answer a question I think very deeply and try my best, hope it helps...
As you know there are many different types of systems. For example, The solar system, galaxies, quantum systems, atoms, molecules, orchestras, nervous system, etc, things you may not have even considered a system. To get to the basis of a system we must first understand what a system is then we will show some examples. A system is a group of Parts (parts could mean anything even dark energy and dark matter) that work together to accomplish something. For example, your body has many many trillions of cells that all try to accomplish the functions of humans which include thinking, moving, breathing, circulation, etc. Cells in turn are a system that have counterparts called organelles that accomplish harvesting energy, making new proteins, getting rid of waste, and so on. These are some systems which we highly dependent upon. 
Well i hope it helped
Spiky Bob your answerer 
 
        
             
        
        
        
Answer:
a. one-half as great 
Explanation:
The power developed by the first lifter is one-half as great as that of the second person. 
   Power is defined as the rate at which work is done; 
           Power  =  
 
Since the two lifters do the same work at different time, let us estimate their power;
        P₁ =  P₂ =
                     P₂ =  
 
    We see that for P₁, power is half of the work done whereas in P₂ power is the same as the work done. 
Therefore, 
            The power of the first weight lifter is one-half the second lifter. 
 
        
             
        
        
        
Answer:
D. Downshift to allow you to turn more sharply
 
        
             
        
        
        
You are correct earth science is studied to predict planetery changes