Engineering Science N3 Heat

Question 1

What is heat?

Answer 1

Heat is a form of energy that flows from a hot object to a cold object.

Question 2

What is the SI unit of heat?

Answer 2

The SI unit of heat is the Joule (J).

Question 3

True or False: Heat always flows from a cold object to a hot object.

Answer 3

False

Question 4

Define specific heat capacity.

Answer 4

Specific heat capacity is the amount of heat required to raise the temperature of 1 kg of a substance by 1 degree Celsius.

Question 5

What is thermal conductivity?

Answer 5

Thermal conductivity is the property of a material that determines how well it can conduct heat.

Question 6

What is conduction?

Answer 6

Conduction is the transfer of heat through a material without the material itself moving.

Question 7

What is convection?

Answer 7

Convection is the transfer of heat through the movement of fluids (liquids or gases).

Question 8

What is radiation?

Answer 8

Radiation is the transfer of heat through electromagnetic waves.

Question 9

What is the formula for calculating heat energy?

Answer 9

Heat energy (Q) = mass (m) x specific heat capacity (c) x temperature change (ΔT)

Question 10

What is the formula for calculating thermal efficiency?

Answer 10

Thermal efficiency = (useful output energy / input energy) x 100%

Question 11

What is the zeroth law of thermodynamics?

Answer 11

If two systems are in thermal equilibrium with a third system, they are in thermal equilibrium with each other.

Question 12

What is the first law of thermodynamics?

Answer 12

The first law of thermodynamics states that energy cannot be created or destroyed, only transferred or transformed.

Question 13

What is the second law of thermodynamics?

Answer 13

The second law of thermodynamics states that heat always flows from hot to cold objects and that entropy increases over time.

Question 14

What is the third law of thermodynamics?

Answer 14

The third law of thermodynamics states that the entropy of a perfect crystal at absolute zero is zero.

Question 15

Define heat capacity.

Answer 15

Heat capacity is the amount of heat required to raise the temperature of an object by 1 degree Celsius.

Question 16

What is the difference between heat and temperature?

Answer 16

Heat is the transfer of energy between objects due to a temperature difference, while temperature is a measure of the average kinetic energy of particles in a substance.

Question 17

What is a heat exchanger?

Answer 17

A heat exchanger is a device used to transfer heat between two or more fluids.

Question 18

What is the Carnot cycle?

Answer 18

The Carnot cycle is a theoretical thermodynamic cycle that is the most efficient cycle possible for converting heat into work.

Question 19

What is the Stefan-Boltzmann law?

Answer 19

The Stefan-Boltzmann law states that the total energy radiated per unit surface area of a black body is proportional to the fourth power of the body’s absolute temperature.

Question 20

What is the greenhouse effect?

Answer 20

The greenhouse effect is the process by which radiation from a planet’s atmosphere warms the planet’s surface to a temperature above what it would be without its atmosphere.

Question 21

What is a heat pump?

Answer 21

A heat pump is a device that transfers heat from a colder area to a hotter area.

Question 22

What is thermal expansion?

Answer 22

Thermal expansion is the tendency of matter to change in volume in response to a change in temperature.

Question 23

What is the ideal gas law?

Answer 23

The ideal gas law is the equation of state of a hypothetical ideal gas, PV = nRT, where P is pressure, V is volume, n is the number of moles, R is the gas constant, and T is temperature.

Question 24

What is a heat sink?

Answer 24

A heat sink is a passive heat exchanger that transfers the heat generated by an electronic or mechanical device to a fluid medium.

Question 25

What is the principle of conservation of energy?

Answer 25

The principle of conservation of energy states that energy cannot be created or destroyed, only converted from one form to another.

Question 26

What is the conservation of energy