Consider two identical iron nails: one nail is heated to 95 °c, the other is cooled to 15 °c. the two nails are placed in a coffee cup calorimeter and the system is allowed to come to thermal equilibrium. what is the final temperature of the two nails

The heat released or absorbed by a substance is calculated through the equation,
     H = mcpdT

where H is teh heat,
   m is the mass,
  Cp is the specific heat, and 
  dT is the temperature difference

In this item, since both nails are identical, m and cp for both nails are equal such that the equation can be expressed as,
    mcp(95 - x) = mcp(x - 15)

where x is the final temperature. Solving for the value of x from the equation derived above will give us a final answer of 55 degrees C. 

55°

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