A steel ball is brought in contact with an identical ball of wood, so when will they be equally hot or cold? why?

Who says they were not at the same temperature at the beginning? If they were not, then heat will flow from the high temperature ball to the low temperature ball until they reach the same temperature. The time depends on the contact area between the two balls as well as the initial temperature difference.

at room temperature

The steel ball and the wooden ball will be equally hot or cold when they reach thermal equilibrium. Thermal equilibrium occurs when there is no net flow of heat between two objects in contact, and they reach the same temperature.

To understand when this equilibrium will be reached, we need to consider a few factors. The rate at which heat is transferred between the steel and wooden balls depends on their thermal conductivity, specific heat capacity, and the temperature difference between them.

1. Thermal Conductivity: Steel has a higher thermal conductivity compared to wood. This means that heat transfers more quickly through the steel ball than through the wooden ball. As a result, the steel ball will gain or lose heat faster than the wooden ball.

2. Specific Heat Capacity: Specific heat capacity is the amount of heat required to raise the temperature of a given substance by a certain amount. Steel has a lower specific heat capacity compared to wood. This means that it takes less heat to raise the temperature of the steel ball than the wooden ball.

3. Temperature Difference: The initial temperature difference between the steel ball and the wooden ball also affects the time required to reach thermal equilibrium. The larger the temperature difference, the longer it will take for the two balls to reach the same temperature.

Given these factors, we can conclude that the steel ball will heat up or cool down faster than the wooden ball when they are brought into contact. However, the exact time it takes for them to reach thermal equilibrium will depend on the specific properties of the materials and the temperature difference between them.