Answer:
final temperature = 26.5°
Explanation:
The water's initial volume is calculated as 1 x 1 x 1 = 1 
The starting temperature of the water is 20° C
Water density = 1000 kg/
Volume of the copper block is determined as 0.46 x 0.46 x 0.46 = 0.097 
The copper block's initial temperature is 100° C
Copper density = 8960 kg/
The water's final volume after accounting for the copper block is 1 - 0.097 = 0.903 
Assumptions:
- the tank is adiabatic, meaning there’s no heat exchange through its walls
- the tank is completely filled, lacking space for any air to cool the water
- the total thermal energy in the tank is comprised of both the water’s heat energy and that of the copper block.
The mass of the remaining water in the tank can be calculated using density x volume = 1000 x 0.903 = 903 kg
The specific heat capacity for water, c = 4186 J/K-kg
Total heat content of the water Hw = mcT = 903 x 4186 x 20 = 75.59 Mega-joules
The copper's mass is calculated as density x volume = 8960 x 0.097 = 869.12 kg
Copper's specific heat capacity is 385 J/K-kg
The heat content of copper Hc = mcT = 869.12 x 385 x 100 = 33.46 Mega-joules
The overall heat in the system totals up to 75.59 + 33.46 = 109.05 Mega-joules
This heat will be evenly dispersed across the system
The heat energy of the water in the system is expressed as mcT
where T signifies the final temperature
= 903 x 4186 x T = 3779958T
For copper, the heat will be
mcT = 869.12 x 385 = 334611.2T
The combined heat from both will equal the total heat of the system, meaning
3779958T + 334611.2T = 109.05 x 
4114569.2T = 109.05 x 
Thus, the final temperature T = (109.05 x
)/4114569.2 = 26.5°