Answer:
The chance in distance is 25 knots
Explanation:
The distance between the two particles is given by:
 (1)
  (1) 
Since A is traveling north and B is traveling east we can say that their displacement vector are perpendicular and therefore (1) transformed as:
 (2)
 (2)
Taking the differential with respect to time:
 (3)
  (3)
where  and
 and  are the respective given velocities of the boats. To find
 are the respective given velocities of the boats. To find  and
 and  we make use of the given position for A,
 we make use of the given position for A,  , the Pythagoras theorem and the relation between distance and velocity for a movement with constant velocity.
, the Pythagoras theorem and the relation between distance and velocity for a movement with constant velocity.

with this time, we know can now calculate the distance at which B is:

and applying Pythagoras: 

Now substituting all the values in (3) and solving for   we get:
 we get:

 
        
             
        
        
        
It can be caused by chemical reactions like sulfur dioxide and nitrogen oxides. These can rise very high in the atmosphere. They can mix in with oxygen and rain and thats where you get your acid rain from
I hope this is helpful <span />
        
                    
             
        
        
        
Answer:
D.
a control group
Explanation:
In a scientific experiment such as the one above, there is an experimental group and a control group. The experimental group is the group that receives the treatment while the control group does not receive any treatment. The control group helps the researcher to observe if the treatment had any significant effect. 
In this case, it will help Alan and Monica to determine if fertilizer X actually had an effect on the plant. Therefore, the pot with o grams of fertilizer in it is the control group.