## Saturday, 20 September 2014

### THERMAL PHYSICS QUESTIONS

1.       Which two values of temperature are equivalent to the nearest degree when measured on the Kelvin and on the Celsius scales of temperature?
 Kelvin scale Celsius scale A. 40 313 B. 273 100 C. 313 40 D. 373 0
2.       A substance changes from solid to liquid at its normal melting temperature. What change, if any, occurs in the average kinetic energy and the average potential energy of its molecules?
 Average kinetic energy Average potential energy A. constant constant B. increases constant C. increases decreases D. constant increases
3.       The specific latent heat of vaporization of a substance is greater than its specific latent heat of fusion because
A.      boiling takes place at a higher temperature than melting.
B.      thermal energy is required to raise the temperature from the melting point to the boiling point.
C.      the volume of the substance decreases on freezing but increases when boiling.
D.      the increase in potential energy of the molecules is greater on boiling than on melting.
4.       The kelvin temperature of an object is a measure of
A.      the total energy of the molecules of the object.
B.      the total kinetic energy of the molecules of the object.
C.      the maximum energy of the molecules of the object.
D.      the average kinetic energy of the molecules of the object.
5.       Some liquid is contained in a shallow dish that is open to the atmosphere. The rate of evaporation of the liquid does not depend on
A.      the temperature of the liquid.
B.      the temperature of the atmosphere.
C.      the depth of the liquid.
D.      the pressure of the atmosphere.

6.      The internal energy of a solid substance is equal to the
A.      average kinetic energy of the molecules.
B.      total kinetic energy of the molecules.
C.      total potential energy of the molecules.
D.      total potential and total kinetic energy of the molecules

7.       Which of the following correctly shows the changes, if any, in the potential energy and in the kinetic energy of the molecules of a solid as it melts?
 Potential energy Kinetic energy A. Decreases Increases B. Increases Stays the same C. Stays the same Decreases D. Stays the same Stays the same

8.Explain what is meant by the temperature of a substance.