Answer:

Explanation:
We should first find the velocity and acceleration functions. The velocity function is the derivative of the position function with respect to time, and the acceleration function is the derivative of the velocity function with respect to time. 

Similarly, 

Now, the angle between velocity and acceleration vectors can be found. 
The angle between any two vectors can be found by scalar product of them: 

So, 

At time t = 0, this equation becomes

 
        
             
        
        
        
A. <span>Standing is health-enhancing because it uses energy.
Because standing can burn a lot of calories.</span>
 
        
        
        
The feather's vertical position  is determined by
 is determined by

We take the feather's starting position to be the origin, and the downward direction to be positive. Then

so the answer is D.
 
        
             
        
        
        
Limited resources: resources that take a long time to replenish
Example: coal, oil, nuclear gas
Non- limited resource: resources that are constantly being replenished
Example: soil, wind, water