Two samples of carbon come into contact. A heat transfer will occur between sample A and sample B. What must be true for heat to transfer from sample A to sample B?
The average kinetic energy of A is greater than that of B.
The average kinetic energy of B is greater than that of A.
The average kinetic energy of both samples is equal.
The average kinetic energy does not determine the direction of heat transfer.

The average kinetic energy of A is greater than that of B.

Explanation:

The temperature of an object is directly proportional to the average kinetic energy of the particles in the object. For instance, for an ideal gas, we have

where

KE is the kinetic energy

k is the Boltzmann constant

T the absolute temperature of the gas

Therefore, this means that in a hotter object the average kinetic energy of the particles is higher than the average kinetic energy of the particles in a colder object.

Moreover, the laws of thermodynamics tell us that heat is always transferred from a hotter object (higher temperature) to a colder object (lower temperature).

In this problem heat is transferred from sample A to sample B. Therefore, this means that object A has higher temperature, and therefore, higher average kinetic energy. So the correct answer is

The average kinetic energy of A is greater than that of B.

explanation:

0.07 g/cm³

1.37 g/cm³