Internal Energy and Temperature 40-41

Question 1

Explain thermal equilibrium

Answer 1

Suppose A, B and C are three identical metal blocks. A has been in a warm oven, B has become from a refrigerator and C is at room temperature. Thermal energy flows from A to C and C to B until they all reach thermal equilibrium and the net flow of energy stops. This happens when the three blocks are at the same temperature. Thermal energy is always transferred from regions of higher temperature to regions of lower temperature.

Question 2

Define the term specific thermal capacity (c) of a substance.

Answer 2

The specific thermal capacity(c) of a substance is the amount of energy needed to raise the temperature of 1kg of the substance by 1k (or 1*C).

Question 3

Write the equation for the energy change in thermal energy.

Answer 3

E = mcT

• E is the energy change in J
• m is the mass in kg
• T is the temperature change in K or *C.
• Units of c are j Kg^-1K^-1 or J Kg^-1 *C^-1

Question 4

Draw the graph of speed distribution of particles for a lower temperature and a higher temperature.

( proportion of particles with given speed vs particle speed.)

Explain the changes to the distribution of particles graph when the temperature is increased.

Answer 4

1) The average particle speed increases.
2) The maximum particle speed increases
3) The distribution curve curve becomes more spread out.

Question 5

What is internal energy?

Answer 5

Internal energy is the sum of the kinetic and potential energy of the particles within a system.

Question 6

What is the equation that comes from equating the ideal gas equation and the equation involving the mean square of the particles?

Answer 6

1/2 mc² = 3/2 nRT/N

Question 7

Why will a rise in the absolute temperature will cause an increase in internal energy?

Answer 7

A rise in absolute temperautre will cause an increase in the kintetic energy of each particle, meaning a rise in internal energy.