Question

Place a kilogram block of iron at 40 degrees C into a kilogram of water at 20 degrees C, and the final temperature of the two becomes

a) 25 degrees C
b) 30 degrees C
c) 35 degrees C
d) 40 degrees C

Answer 1

Option C: The final temperature when a kilogram block of iron at 40 degrees C is placed in a kilogram of water at 20 degrees C is 35 degrees C.

Step-by-step explanation:

To find the final temperature when a kilogram block of iron at 40 degrees C is placed in a kilogram of water at 20 degrees C, we can use the principle of conservation of energy. The heat gained by the water must be equal to the heat lost by the iron. We can calculate the heat gained by the water using the formula Q = mcΔT, where Q is the heat gained, m is the mass, c is the specific heat capacity, and ΔT is the change in temperature. This can be calculated using the principle of conservation of energy and the specific heat capacities of water and iron.

Given that the specific heat capacity of water is 4186 J/kg°C and the specific heat capacity of iron is 450 J/kg°C, we can calculate:

1. Heat gained by water: Q_water = (1 kg)(4186 J/kg°C)(T_final - 20)
2. Heat lost by iron: Q_iron = (1 kg)(450 J/kg°C)(40 - T_final)
3. Setting Q_water = Q_iron and solving for T_final:

T_final = 35 degrees C (Option c)