Answer:
Explanation:
Given
Weight of roller coaster is 
mass of roller coaster 
Distance traveled by roller coaster 
drag force 
velocity at top 
Suppose E is the initial energy
Conserving Energy at bottom and top 



 
        
             
        
        
        
The sharp nail has a less surface area in comparison to a blunt nail and pressure is inversely proportional to area so it is easier to Hamer a sharp  nail into a wood rather than having a blunt nail in wood
 
        
             
        
        
        
Answer:
Explanation:
It would actually be A. 30 , as each hour of ascension (i am not sure about the correct terminology) equals 15 .