Potential energy due to gravity
        
                    
             
        
        
        
Answer: 7291.2 joules 
Explanation:
Work is done when force is applied on an object over a distance. 
Thus, Workdone = Force X distance 
Since Distance moved by box = 12 metres 
mass of box = 62kg 
Acceleration due to gravity when box was lifted is represented by g = 9.8m/s^2
Recall that Force = Mass x acceleration due to gravity 
i.e Force = 62kg x 9.8m/s^2
= 607.6 Newton 
So, Workdone = Force X Distance 
Workdone = 607.6 Newton X 12 metres
Workdone = 7291.2 joules 
Thus, 7291.2 joules of work was done. 
 
        
             
        
        
        
no, it not useless. we still learn Bohr's model in HS n dats almost 200 yr old! while there may be new models, previous one is good for explaining the basics. it is also useful to learn previous model n see how our understanding improves over time.
 
        
                    
             
        
        
        
Answer:
Q = 913.9 gpm
Explanation:
The Hazen Williams equation can be written as follows:

where,
P = Friction Loss per foot of pipe =  = 4 x 10⁻⁴
 = 4 x 10⁻⁴
Q = Flow Rate in gallon/min (gpm) = ?
d = pipe diameter in inches = (400 mm)(0.0393701 in/1 mm) = 15.75 in
C = roughness coefficient = 100 
Therefore,

<u>Q = 913.9 gpm</u>