Question

3kg of water at 60degrees is mixed with the of water
at 40 degrees Find
the temperature of mixtures.​

Answer 1

Generally, specific heat is a function of temperature itself. But, in current problem variation of 20 degree C will not change the value of specific heat significantly. A simple energy balance is used for the system(assuming there is no transfer of heat to the surrounding):

50*4.2*(40-T)= 75*4.2*(T-20)

T= 28 C

(Strictly speaking, in real scenario temperature of water will be less than 28 degree C, because some part of heat will be transferred to the surrounding. This the maximum limit of the temperature which can be attained at thermal equilibrium.)