Determine the specific heat of copper if, upon cooling 3 kg of copper, 2340 J of heat was released by 2 K.

The amount of heat spent on heating the body is equal to the product of the specific heat capacity of the substance, body weight and the difference between the final and initial temperatures.
Q = c * m * (t2-t1), where c is the specific heat capacity of the substance, m is the mass of the substance, t2 and t1 are the final and initial temperatures, respectively.
Let us express c from this expression, substitute the numbers and find the heat capacity of copper:
c = Q / (m * (t2-t1)) = 2340 / (3 * 2) = 390 J / (kg * K)
Answer: 390 J / (kg * K).