Answer:
50J
Explanation:
At the top you have(A) 
KE_a = O
PE_a = 100J
KE + PE = 100J
At the bottom you have (C)
KE_c= 100J
PE_c=0J
KE+PE = 100J
At point C:
You are at half the height.
We know that at H, PE =100J
PE_c = mgH
At C,
PE_c= mg (H/2) *at half the height
*m and g stay the same
Intuitively, the higher you are, the more potential energy you have.
If you decrease the height by a half, your PE will also decrease
At A:
PE_a / (mg) = H
At B:
PE_b / (mg) = H/2
to also get H on the right hand side, multiply by 2
2 (PE_b/ (mg))= H
2PE_b / (mg) = H
Ok, now that we have set up 2 equations (where H is isolated), find PE at B
AT A = AT B *This way you are saying that H = H (you compare both equations)
PE_a / (mg) = 2x PE_b / (mg)
*mg are the same for both cancel them (you can do that because of the = sign)
PE_a =  2PE_b
We know that PE_a = 100J
100J/2 = PE_b
PE at b = 50J
**FIND KE at b
We know that 
KE_b + PE_b is always 100J
100J = 50J + KE_b
KE_b = 50J
 
        
             
        
        
        
I don't know for sure but i think that it is because the force him pushing her pushed him back as well
Hope i helped
        
                    
             
        
        
        
Answer:
The molar mass of a compound tells you the mass of one mole of that substance. In other words, it tells you the number of grams per mole of a compound.
 
        
             
        
        
        
Is that a question? If it is not what its the question?
        
             
        
        
        
There are approximately 3 different types of atoms that are present in one molecule of aluminum hydroxide, AI(OH)3.