Answer:
the potential energy is 114 J.
Explanation:
Given;
total mechanical energy, E = 400 J
kinetic energy, K.E = 286 J
The potential energy is calculated as follows;
E = K.E +  P.E
where;
P.E is the potential energy 
P.E = E - K.E
P.E = 400 J - 286 J
P.E = 114 J
Therefore, the potential energy is 114 J.
 
        
             
        
        
        
Decreases the input force
        
             
        
        
        
Given :
Vector A has a magnitude of 63 units and points west, while vector B has the same magnitude and points due south.
To Find :
The magnitude and direction of 
a) A + B .
 b) A - B. 
Solution :
Let , direction in north is given by +j and east is given by +i .
So ,  and
 and 
Now , A + B is given by :


Direction of A+B is 45° north of west .
Also , for A-B :


Direction of A-B is 45° south of west .
( When two vector of same magnitude which are perpendicular to each other are added or subtracted the resultant is always 45° from each of them)
Hence , this is the required solution .
 
        
             
        
        
        
145 Grams!
It asks for the “Total Mass” basically asking to add, If you add 20 to 125, you get 145! Correct me if im wrong
        
             
        
        
        
Answer:
v = wavelength * frequency
frequency = 5200 m/s / .2 m = 26000 / sec
20,000 / sec is optimistic for the upper frequency of human hearing
So 26,000 is above the hearing range for human ears