Quick Review Flashcards - Click to flip and test your knowledge!
Question
How is heat produced when two palms are rubbed against each other?
Answer
Heat is produced by doing mechanical work.
Question
From which form of energy is heat obtained when an electric current passes through a metallic wire?
Answer
Heat is obtained from electrical energy.
Question
The internal energy of a body consists of the sum of total molecular kinetic energy and total _____.
Answer
Molecular potential energy
Question
Define 'heat' as a form of energy.
Answer
Heat is the form of energy that is transferred between two bodies at two different temperatures when kept in contact.
Question
What is the S.I. unit of heat?
Answer
The S.I. unit of heat is the joule ($J$).
Question
What is the C.G.S. unit of heat?
Answer
The C.G.S. unit of heat is the erg.
Question
State the mathematical relationship between 1 joule ($J$) and ergs.
Answer
$1\ J = 10^{7}\ erg$
Question
What is the exact relationship between 1 calorie ($cal$) and joules ($J$)?
Answer
$1\ cal = 4.186\ J$
Question
How many calories are equivalent to 1 kilocalorie ($kcal$)?
Answer
$1000\ calories$
Question
In which direction does heat flow when a hot body and a cold body are placed in contact?
Answer
Heat flows from the hot body to the cold body.
Question
Term: Temperature
Answer
Definition: A quantity which indicates the thermal state of a body and determines the direction of heat flow between bodies.
Question
What happens to the particles of a body when it receives heat energy?
Answer
The particles start vibrating more vigorously and their average kinetic energy increases.
Question
Two bodies are said to be at the same temperature if there is no _____ between them when placed in contact.
Answer
Transfer of heat
Question
On what three factors does the amount of heat energy contained in a body depend?
Answer
It depends on the mass, temperature, and nature of the material of the body.
Question
What is the S.I. unit of temperature?
Answer
The S.I. unit of temperature is the kelvin ($K$).
Question
Formula: Conversion of temperature from Celsius ($t\ ^{\circ}C$) to Kelvin ($T\ K$)
Answer
$T\ K = 273 + t\ ^{\circ}C$
Question
Why is a negative temperature not possible on the Kelvin scale?
Answer
Because $0\ K$ is the absolute zero temperature where molecular motion ceases.
Question
What is the temperature of the 'ice point' on the Fahrenheit scale?
Answer
$32^{\circ}F$
Question
What is the temperature of the 'steam point' on the Kelvin scale?
Answer
$373\ K$
Question
How many equal divisions exist between the ice point and steam point on the Fahrenheit scale?
Answer
180 equal divisions
Question
One degree on the Celsius scale is equal to _____ degrees on the Fahrenheit scale.
Answer
$\frac{9}{5}$
Question
Formula: Relationship between Celsius ($C$) and Fahrenheit ($F$) scales
Answer
$\frac{C}{5} = \frac{F - 32}{9}$
Question
How does the dependency of temperature differ from the dependency of heat regarding molecular motion?
Answer
Heat depends on the total motion of molecules, while temperature depends on the average kinetic energy of molecules.
Question
Which physical principle is used to measure heat?
Answer
The principle of calorimetry.
Question
True or False: Two bodies with the same quantity of heat must have the same temperature.
Answer
False, they may differ in their temperature.
Question
Term: Thermal Expansion
Answer
Definition: The expansion of a substance when it is heated.
Question
What is the specific name for the increase in area of a solid upon heating?
Answer
Superficial expansion
Question
Why do liquids and gases only exhibit cubical expansion?
Answer
Liquids and gases do not have a definite shape.
Question
Rank solids, liquids, and gases in order of their typical magnitude of expansion upon heating, from least to most.
Answer
Solids < Liquids < Gases
Question
Term: Anomalous Expansion of Water
Answer
Definition: The unusual expansion of water when it is cooled from $4^{\circ}C$ down to $0^{\circ}C$.
Question
At what specific temperature does water reach its minimum volume?
Answer
$4^{\circ}C$
Question
What is the volume of $1\ g$ of water at $4^{\circ}C$?
Answer
$1.0000\ cm^{3}$
Question
At what temperature is the density of water at its maximum?
Answer
$4^{\circ}C$
Question
State the value of the maximum density of water in S.I. units.
Answer
$1000\ kg\ m^{-3}$
Question
What happens to the density of water as it is heated from $0^{\circ}C$ to $4^{\circ}C$?
Answer
The density increases.
Question
Which scientific apparatus is used to demonstrate the anomalous expansion of water?
Answer
Hope's apparatus
Question
In Hope's experiment, where is the freezing mixture of ice and salt placed?
Answer
In a cylindrical trough surrounding the central part of the metallic cylinder.
Question
In Hope's experiment, what is the final steady temperature recorded by the lower thermometer ($T_{2}$)?
Answer
$4^{\circ}C$
Question
In Hope's experiment, what is the final steady temperature recorded by the upper thermometer ($T_{1}$)?
Answer
$0^{\circ}C$
Question
Why does cooled water sink to the bottom of the cylinder in Hope's experiment when the temperature is above $4^{\circ}C$?
Answer
Water contracts and its density increases, causing the heavier water to sink.
Question
During Hope's experiment, why does the reading of the upper thermometer ($T_{1}$) only start to fall rapidly after the lower part reaches $4^{\circ}C$?
Answer
Below $4^{\circ}C$, water expands and its density decreases, causing the colder water to rise toward the top.
Question
How does the anomalous expansion of water help preserve aquatic life in very cold weather?
Answer
Ice forms at the surface and acts as an insulator, while the water at the bottom remains at $4^{\circ}C$.
Question
Why do water pipelines often burst in colder countries during winter nights?
Answer
When water freezes into ice below $4^{\circ}C$, it expands and exerts great pressure on the pipe walls.
Question
How can farmers protect plants from dying when temperatures drop below $4^{\circ}C$?
Answer
Fields are filled with water to prevent the plant capillaries from bursting due to freezing and expansion.
Question
Term: Greenhouse Effect
Answer
Definition: The process of warming the Earth's surface and lower atmosphere by the absorption of long-wavelength infrared radiations emitted from the surface.
Question
Which scientist discovered the greenhouse effect in 1896?
Answer
Svante Arrhenius
Question
The Earth's atmosphere is transparent to solar radiations of _____ wavelength, such as visible light.
Answer
Short
Question
Why are greenhouse gases like $CO_{2}$ able to trap heat in the atmosphere?
Answer
They are good absorbers of the long-wavelength infrared radiations emitted by the Earth.
Question
Name four primary greenhouse gases found in the Earth's atmosphere.
Answer
Carbon dioxide, methane, nitrous oxide, and chlorofluorocarbons ($CFCs$).
Question
What would be the average temperature on Earth's surface in the total absence of greenhouse gases?
Answer
$-18^{\circ}C$ (or $0^{\circ}F$)
Question
What is the current average temperature on the Earth's surface due to the natural greenhouse effect?
Answer
$15.5^{\circ}C$ (or $60^{\circ}F$)
Question
Term: Global Warming
Answer
Definition: The increase in average effective temperature near the Earth's surface due to an increase in the amount of greenhouse gases.
Question
By how much has the global average surface temperature increased since the pre-industrial era?
Answer
$1^{\circ}C$
Question
Identify one human activity responsible for the increase of carbon dioxide in the atmosphere.
Answer
The burning of fossil fuels (coal, petroleum, and natural gas).
Question
How does deforestation contribute to global warming?
Answer
It reduces the number of trees available to absorb $CO_{2}$ and converts them into oxygen.
Question
Which greenhouse gas is primarily released from rice cultivation and animal husbandry?
Answer
Methane ($CH_{4}$)
Question
What is the expected impact of global warming on the world's plant and animal species by the year 2100?
Answer
Up to 70% of plant and animal species may vanish.
Question
Why is global warming expected to cause a decrease in the amount of oxygen dissolved in oceans?
Answer
The warming of ocean waters reduces the solubility of oxygen.
Question
How will global warming affect farming in low-latitude regions?
Answer
It will result in poor crop yields and increased malnutrition.
Question
Which technological measure can be taken to reduce $CO_{2}$ emissions from power plants?
Answer
Use of renewable sources of energy like wind, solar, and tidal energy.