Physics Heat Transfer Quiz

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Questions and Answers

What is the effect of heating a gas or vapor on its molecules?

The molecules bond together to form a solid.

The molecules slow down and lose kinetic energy.

The molecules speed up and gain kinetic energy. (correct)

The molecules remain at the same speed but change direction.

What is internal energy?

The energy stored in the chemical bonds of a substance.

The energy released when a substance undergoes a chemical reaction.

The energy associated with the motion of the object as a whole.

The total energy of an object, including its kinetic and potential energy. (correct)

What two factors determine the temperature rise of an object when it is heated?

The mass of the object and the amount of energy supplied.

The amount of energy supplied and the substance the object is made from.

The mass of the object and the substance the object is made from.

All of the above. (correct)

What is the specific heat capacity of a substance?

The energy required to raise the temperature of 1 kg of the substance by 1 K. (B) Signup and view all the answers

Why does sand heat up faster than water?

Sand has a lower specific heat capacity than water. (B) Signup and view all the answers

In the inversion tube experiment, what is the source of the internal energy gain in the lead shot?

The conversion of gravitational potential energy. (C) Signup and view all the answers

In the inversion tube experiment, what is the relationship between the gravitational potential energy loss and the internal energy gain of the lead shot?

The gravitational potential energy loss is equal to the internal energy gain. (C) Signup and view all the answers

What is the formula for calculating the specific heat capacity (c) of the lead shot in the inversion tube experiment?

c = gLn/Δθ (B) Signup and view all the answers

Which of the following is NOT an example of convection?

A metal rod heated at one end (D) Signup and view all the answers

Why is a metal a better conductor of heat than a non-metal?

Metals have free electrons that can transfer energy (D) Signup and view all the answers

In what way does the density of a fluid affect its ability to transfer heat by convection?

Denser fluids transfer heat more efficiently (D) Signup and view all the answers

Which of the following is essential for the safe use of a gas fire?

Adequate ventilation to remove combustion products (C) Signup and view all the answers

Which of the following is a FALSE statement about heat transfer by conduction?

It occurs through the movement of fluids (D) Signup and view all the answers

Which of the following scenarios would lead to the most efficient heat transfer by convection?

Heating a pot of water with a strong fan blowing across the surface (A) Signup and view all the answers

Why is it important to ensure that a hot air balloon is constantly heated?

To create lift and allow the balloon to rise (A) Signup and view all the answers

Which of the following statements correctly describes the relationship between thermal conductivity (K) and U-value?

U-value is directly proportional to K (A) Signup and view all the answers

What is the relationship between work done on a system and the change in internal energy of the system?

Work done on a system can either increase or decrease the internal energy depending on other factors. (A) Signup and view all the answers

Which of the following best describes the motion of molecules in a solid?

Molecules vibrate randomly around fixed positions. (D) Signup and view all the answers

How does the internal energy of a solid change when it melts?

The internal energy increases because the molecules break free from each other. (A) Signup and view all the answers

Which of the following statements accurately describes the relationship between temperature and the motion of molecules in a gas?

The higher the temperature, the faster the molecules move. (A) Signup and view all the answers

What is the change in the internal energy of a system if 100 Joules of heat is added to the system and 50 Joules of work is done by the system?

150 Joules (B) Signup and view all the answers

What is the relationship between the internal energy of a system and the temperature of the system?

Internal energy is directly proportional to temperature. (C) Signup and view all the answers

Which of the following is a correct statement about the first law of thermodynamics?

The first law of thermodynamics states that energy cannot be created or destroyed, only transferred or transformed. (A), The first law of thermodynamics states that energy is always conserved in a closed system. (C), The first law of thermodynamics states that the total energy of an isolated system remains constant. (D) Signup and view all the answers

If a system absorbs heat while doing work, what can be concluded about the change in internal energy of the system?

The change in internal energy cannot be determined without more information. (D) Signup and view all the answers

What type of radiation does every object emit due to its temperature?

Thermal radiation (A) Signup and view all the answers

Which type of surface absorbs thermal radiation most effectively?

Matt black surfaces (C) Signup and view all the answers

What is a black body in the context of radiation?

An object that absorbs all incident radiation (A) Signup and view all the answers

What is the primary factor that the rate of energy loss from a building can be reduced by?

The type of insulation used (A) Signup and view all the answers

What does the U-value indicate in terms of insulation?

The rate of energy transfer through the insulation (D) Signup and view all the answers

How is the energy transfer rate calculated with a temperature difference across insulation?

U × A × ΔΘ (B) Signup and view all the answers

What is the U-value for a typical single-glazed window?

4.3 W m-2K-1 (C) Signup and view all the answers

Which condition is NOT necessary for an object to be classified as a black body?

It must reflect some radiation. (D) Signup and view all the answers

Which of the following is NOT a way to increase the internal energy of an object?

Decreasing the object's temperature (D) Signup and view all the answers

If a vehicle is moving at a constant speed, and its brakes are applied, what happens to the internal energy of the brake pads?

It increases because the brake pads are absorbing energy from the vehicle's kinetic energy. (D) Signup and view all the answers

What is the primary reason for the transfer of energy by heating?

The temperature difference between the objects. (D) Signup and view all the answers

What is the most accurate statement about the internal energy of a lamp filament when it is switched on?

The internal energy increases because work is done by the electricity supply. (D) Signup and view all the answers

Which of the following is NOT a method of energy transfer by heating?

Friction (A) Signup and view all the answers

What is the relationship between the temperature of an object and its internal energy?

Temperature is a measure of the average kinetic energy of the molecules within an object, which can be associated with its internal energy. (A) Signup and view all the answers

How does energy transfer by heating occur between two objects?

The hotter object always transfers energy to the colder object. (A) Signup and view all the answers

How does the electrical energy supplied to the metal block relate to the temperature rise?

The electrical energy supplied is directly proportional to the temperature rise. (A) Signup and view all the answers

In the experiment to measure the specific heat capacity of a liquid, why is it important to assume no heat loss to the surroundings?

To ensure that the electrical energy supplied is entirely used to heat the liquid and the calorimeter. (C) Signup and view all the answers

What is the purpose of the water or oil in the thermometer hole during the experiment?

To improve the thermal contact between the thermometer and the metal. (C) Signup and view all the answers

In the continuous flow heating system, what happens to the energy supplied to the copper coils?

The energy is used to increase the temperature of the water flowing through the coils. (A) Signup and view all the answers

Why is there no mcΔΘ term for the copper coils in the equation for continuous flow heating?

The copper coils reach a steady temperature and do not undergo a temperature change. (A) Signup and view all the answers

In the experiment to measure the specific heat capacity of a liquid using an insulated calorimeter, which of the following quantities are NOT required?

Initial temperature of the liquid. (A) Signup and view all the answers

What is the main difference between measuring the specific heat capacity of a metal block and a liquid?

The metal block is heated directly by the electric heater, while the liquid is heated indirectly through the calorimeter. (D) Signup and view all the answers

Which of the following would be the most likely reason for a discrepancy in the calculated specific heat capacity of a liquid?

Not taking into account the heat loss to the surroundings. (A) Signup and view all the answers

Study Notes

Internal Energy and Temperature

Internal energy is the total energy of the molecules in an object due to their individual movements and positions
Thermal energy is a form of internal energy related to temperature
Internal energy increases with heating or work done on an object
If internal energy is constant, there is no energy transfer by heating or work balanced

First Law of Thermodynamics

The change in internal energy of an object equals the total energy transferred due to work done on/by the object and heating
ΔU = Q + W, where Q is energy transfer by heating and W is work done

Molecules

Molecules are the smallest fundamental particles of a substance
Atoms make up molecules
Molecules are held together by forces due to electrical charges between atoms
Molecules in a solid vibrate randomly at fixed positions
Molecules in a liquid move randomly and freely
Molecules in a gas move randomly at high speeds with much greater distance between each other

Temperature and Temperature Scales

Temperature is a measure of the degree of hotness
Hotter objects have more internal energy
No overall energy transfer takes place if objects are at the same temperature (thermal equilibrium)
Celsius scale is defined by ice point (0°C) and steam point (100°C)
Absolute scale (Kelvin) is defined by absolute zero (0K) and triple point of water (273.16K)
°C = K - 273.15

Specific Heat Capacity

Specific heat capacity (c) is the energy needed to raise the temperature of unit mass of a substance by 1K without changing its state
Measured in J kg⁻¹K⁻¹
The energy needed to raise the temperature of a mass m of a substance from θ₁ to θ₂ is AQ = mc(θ₂ - θ₁)

Change of State

Latent heat is the energy needed to change the state of a substance without changing its temperature
Latent heat of fusion is the energy needed to melt a solid at its melting point
Latent heat of vaporisation is the energy needed to vaporise a liquid at its boiling point

Energy Transfer by Heating

Conduction is energy transfer via heating through a material
Convection is transfer of energy via heating by movement of fluids
Radiation is energy transfer via heating by electromagnetic waves

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Description

Test your knowledge on the principles of heat transfer in physics, including concepts such as internal energy, specific heat capacity, and thermal conduction. This quiz covers various phenomena related to how gases and vapors behave when heated, as well as practical applications in daily life. Perfect for students looking to reinforce their understanding of thermodynamics!