WTMA Heat Transfer and Conduction 3

Question 1

A thermos keeps liquid hot by having a vacuum between its walls. The vacuum mainly prevents heat loss by:

Accepted Answer

Conduction and convection

Answer

A vacuum eliminates the medium needed for conduction and convection, preventing both modes of heat transfer.

Question 2

Heat flows from a hot object to a cool object. What happens when they reach the same temperature?

Accepted Answer

Heat flow stops because there is no temperature difference

Answer

Heat transfer stops when thermal equilibrium is reached—no temperature difference means no net heat flow.

Question 3

A steel bolt conducts more heat than a rubber gasket of the same size because steel has:

Accepted Answer

Higher thermal conductivity

Answer

Thermal conductivity is the material property that determines how well a substance conducts heat.

Question 4

Which situation would cause heat to conduct most rapidly through a wall?

Accepted Answer

Thin wall, large temperature difference

Answer

Conduction rate increases with larger temperature differences and decreases with greater thickness.

Question 5

A machinist touches both a metal workbench and a rubber mat at the same room temperature. The metal feels colder because:

Accepted Answer

Metal conducts heat away from the hand faster

Answer

Metal's high conductivity draws heat from your skin rapidly, creating the sensation of cold even at the same temperature.

WTMA - Wiesen Test of Mechanical Aptitude Practice Test