the awnser to ur question is D
 
        
             
        
        
        
Answer:
     K = m g (A - A2)
Explanation:
In a block spring system the total energy is the sum of the potential energy plus the kinetic energy, for maximum elongation all the energy is potential
          Em = U₀ = m g A
For when the system is at an ele
Elongation A2 less than A, energy has two parts
         Em = K + U₂
        K = Em –U₂
We substitute
      K = m g A - m gA2
     K = m g (A - A2)
 
        
                    
             
        
        
        
Answer:

Explanation:
According to the free body diagram, in this case, we have:

Recall that the force of friction is given by:

Replacing and solving for the coefficient of kinetic friction:

We have an uniformly accelerated motion. Thus, the acceleration is defined as:

Finally, we calculate  :
:

 
        
             
        
        
        
That can be considered alive.
        
             
        
        
        
Answer:
copper will have more change in temperature as compare with aluminum
Explanation:
Hot piece of copper is made in contact with cold piece of aluminium 
So here thermal energy transfer will take place from copper to aluminium
so by energy conservation we can say that heat given by copper is same as the heat absorbed by aluminium.
now we have

here we know that
 = specific heat capacity of copper
 = specific heat capacity of copper
 = specific heat capacity of aluminum
 = specific heat capacity of aluminum
given that specific heat capacity of aluminium is more than double that of copper
so we can say

so here if the mass of copper and aluminium is same then

so temperature change of copper is twice the temperature change of aluminium
So copper will have more change in temperature as compare with aluminum