Answer:
<em>0.3c</em>
<em></em>
Explanation:
The speed of Enterprise relative to Risa is 0.8c
Relative speed of both ships as measured from Enterprise is 0.5c
therefore, relative speed of Astra to Enterprise is 0.8c - 0.5c = <em>0.3c</em>
<em>this is also the relative speed with which Astra approaches the planet Risa since Enterprise's speed was calculated relative to Risa.</em>
 
        
             
        
        
        
Answer:
when the temperatures of the two objects are equal
Explanation:
Thermal equilibrium is achieved between two objects when the temperatures of the two objects are equal. Heat flows from hot to cold objects. When the two objects attain equal temperatures, we say thermal equilibrium has been achieved 
 
        
             
        
        
        
The least number of component of a vector quantity is two. These are the x-component and the y-component. 
The resultant vector, or vector as we refer to it in this item, can be calculated through the equation,
              RV = sqrt ((Vx)² + (Vy)²)
From the equation, it can be noted that if we let Vx equal to zero,
              RV = Vy
Similarly, if we let Vy be equal to zero then,
             RV = Vx
Thus, it is still possible for the vector to become nonzero even if one of its components is zero. 
        
             
        
        
        
D is your answer hope this helps