Answer:
At point A, the cart has high potential energy. At point b, the cart is pulled down by gravity. At point c, the cart gains its highest kinetic energy. At point d, the cart returns back to the same state but with lower potential energy.
 
        
             
        
        
        
<span>The correct answer is: Mechanical Energy
Explanation:
As the guitar strings are plunked, the potential energy stored in the strings has an ability to make them vibrate. When the strings are vibrating, that potential energy is actually converted to the kinetic energy. Hence, the whole phenomena contains both the kinetic energy and the potential energy. The sum of kinetic energy and the potential energy is called Mechanical energy. Therefore, the correct answer is Mechanical Energy.</span>
        
                    
             
        
        
        
Catalytic ozone destruction occurs in the stratosphere where the reactions involving bromine, chlorine, hydrogen, nitrogen and oxygen gases form compounds that destroy the ozone layer. The reactions uses a catalyst (speeds up the reaction) in a two step reaction. considering chlorine the reactions appears as follows;
step 1
 Cl + O3 = ClO + O2 
 step 2
ClO + O = Cl + O2 
Where by chlorine is released to destroy the ozone layer, this takes place many times even with the other elements (hydrogen, bromine, nitrogen) and the end result is a completely destroyed Ozone layer
        
             
        
        
        
Answer:
Given, Apparent weight(W₂)=4.2N
           Weight of liquid displaced (u)=2.5N
           Let weight of body in air = W₁
Solution,
              U=W₁-W₂
               W₁=4.2=2.5=6.7N
∴Weight of body in air is 6.7N