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PHYSICS, M3 EQ-Bank 5

A 50 gram copper ball is placed into an insulated container containing 50 mL of water and immediately sealed. The initial temperature of the metal ball and water is 50°C and 10°C respectively. 

A student hypothesises that since the water and copper ball both have the same mass, the temperature of the metal ball and water, once thermal equilibrium is established, would be 30°C.

When the student measured the temperature inside the container, it was 26°C.

Explain the results of the experiment and why the student's hypothesis is incorrect.   (4 marks)

Show Answers Only

→ Although the masses of the copper ball and water are the same, the specific heat capacities of the objects are different which leads to different changes in temperature.

→ The student’s hypothesis is incorrect as they did not take the specific heat capacity values into account.

→ The specific heat capacity of water is greater than that of copper, thus a greater amount of energy would be required to heat water to a certain temperature than to heat copper to that same temperature.

→ Therefore, when reaching a state of thermal equilibrium, the energy transfer between the copper ball and water cools the copper ball down faster than the water heats up.

→ This leads to the final temperature within the container of 26°C, which is closer to the initial temperature of the water than the copper ball.

Show Worked Solution

→ Although the masses of the copper ball and water are the same, the specific heat capacities of the objects are different which leads to different changes in temperature.

→ The student’s hypothesis is incorrect as they did not take the specific heat capacity values into account.

→ The specific heat capacity of water is greater than that of copper, thus a greater amount of energy would be required to heat water to a certain temperature than to heat copper to that same temperature.

→ Therefore, when reaching a state of thermal equilibrium, the energy transfer between the copper ball and water cools the copper ball down faster than the water heats up.

→ This leads to the final temperature within the container of 26°C, which is closer to the initial temperature of the water than the copper ball.