Quiz 1_Heat Transfer

Rate of Heat Conduction in a specified direction is proportional to:

• material's thermal conductivity

• mass

• temperature gradient

• viscosity

Answer explanation

The rate of heat conduction is governed by Fourier's law, which states it is proportional to the temperature gradient. This means that a greater difference in temperature over a distance leads to increased heat flow.

Below are the coordination systems for specification of temperature location, except

• Spherical

• Cartesian

• Cylindrical

• Triangle

Answer explanation

The correct answer is 'Triangle' because it is not a standard coordinate system for specifying temperature locations. The other options, Spherical, Cartesian, and Cylindrical, are all recognized coordinate systems used in various scientific contexts.

Below are example of transport properties, except

• density

• thermal conductivity

• kinematic viscosity

• temperature

Answer explanation

Density and temperature are not transport properties. Transport properties typically include thermal conductivity and kinematic viscosity, which describe how heat and momentum are transferred in materials.

What is the SI unit of thermal conductivity?

• Watt per meter per Kelvin (W/mK)

• Joule per second (J/s)

• Kelvin per meter (K/m)

• Newton per meter (N/m)

Answer explanation

The SI unit of thermal conductivity is Watt per meter per Kelvin (W/mK), which measures the rate of heat transfer through a material. The other options do not represent thermal conductivity.

Differentiate among steady and transient heat transfer.

Answer explanation

Steady heat transfer occurs when the temperature at any point does not change over time, while transient heat transfer involves changes in temperature at points over time. Thus, steady is constant, and transient is variable.

What is the primary mechanism of heat transfer in solids?

• Conduction

• Convection

• Radiation

• Diffusion

Answer explanation

The primary mechanism of heat transfer in solids is conduction. This process involves the transfer of thermal energy through direct contact of particles, allowing heat to move from hotter to cooler areas within the solid.

Which of the following materials has the highest thermal conductivity?

• Wood

• Glass

• Copper

• Plastic

Answer explanation

Copper has the highest thermal conductivity among the options listed. It is a metal known for its excellent ability to conduct heat, making it far more efficient than wood, glass, or plastic.

In which scenario does convection occur?

• Heating a metal rod

• Boiling water

• Sunlight warming the ground

• Cooling a hot cup of coffee

Answer explanation

Convection occurs in boiling water as hot water rises and cooler water sinks, creating a circulation pattern. This process transfers heat through the fluid, unlike the other scenarios which involve conduction or radiation.