12. Physical Sciences

Question 1

Chemists see the world two ways: on a macroscopic level and on a microscopic level. Differentiate macroscopic and microscopic level.

Answer 1

Macroscopic refers to the world-at-large — all the stuff you can see right now. Microscopic refers to a much smaller level, where gas particles bump into each other and atoms bind together.

Question 2

Each element has its own atomic number that’s equal to the number of…

Answer 2

Each element has its own atomic number that’s equal to the number of protons it has.

If an atom has one proton in its nucleus, it has the atomic number 1. Hydrogen is the only element with just one proton in its nucleus. Magnesium, which has 12 protons in its nucleus, is given the atomic number 12.

Question 3

What are the atomic numbers for common elements such as hydrogen, helium, carbon, nitrogen, and oxygen?

Answer 3

1. Hydrogen (1)
2. Helium (2)
3. Carbon (6)
4. Nitrogen (7)
5. Oxygen (8)

Question 4

What is crystal lattice?

Answer 4

Solids have particles or molecules that are close together and don’t move much, and they have a definite shape. In many cases, that’ s because the molecules are bound together in a very rigid structure of repeating patterns. The structure is called crystal lattice. The molecules are still moving, but not much.

Question 5

What is condensation?

Answer 5

Condensation is the process of a substance changing from a gas to a liquid. Condensation is the first phase change liquids go through as they cool; it is the opposite of evaporation. When glasses fog up when you open the dishwasher, when you see dew on the grass in the morning, or when your cup of cold liquid “sweats” on a hot day, you’re watching liquids condense. These events happen because your glasses, the ground, and your cup are colder than the environment they’re in; they cause water molecules in the air to gather together and form a liquid.

Question 6

What is sublimination and deposition?

Answer 6

Sublimination occurs when a substance goes directly from a solid state to a gaseous state with no liquid state in-between. One example is dry ice. Dry ice is solid carbon dioxide, and it is often used to create a smoke or fog effect in magic shows (and nightclubs). Dry ice turns into a colorless gas, but it creates a white cloud as it evaporates (the white cloud it forms is actually condensation of water vapor in the air because the dry ice is so cold). The reverse of sublimination is called deposition, where a gaseous substance becomes a solid without a liquid state in-between.

Question 7

In chemistry, what is a mixture?

Answer 7

A mixture is a physical combination of pure substances that don’t have a constant composition. The composition of the mixture depends on who makes it. Bread tastes different when it comes from two different bakers because each uses a slightly different mixture even though they use all the same ingredients. In a mixture, though, each substance keeps its own chemical characteristics (the flour, oil, and water keep the same molecular structures from start to finish).

Question 8

In chemistry, what is a chemical reaction?

Answer 8

Chemical reaction is a process that rearranges a substance’s molecular structure. No matter what its physical state, water is still made up of H₂O. But if you compound it with another element, its atoms are redistributed to create a new substance. For example, when iron rusts, a chemical change occurs. The rust isn’t the same molecule as the iron is.

Question 9

There are several types of chemical reactions, but what are the 3 most common chemical reactions?

Answer 9

1. Combination: Combination reactions occur when two or more reactants merge to form one product. One example is the way sodium and chlorine combine to create sodium chloride (that’s the table salt).
2. Decomposition: Decomposition reactions are the opposite of combination reactions because a single compound breaks down into two or more simpler substances. This process happens when water decomposes into hydrogen and oxygen gases, for example.
3. Combustion: Combustion reactions typically involve carbon and oxygen in the process known as burning. This type of reaction occurs in your car, in open fires, and when some people try to cook.

Question 10

In chemistry, what is a base and an acid?

Answer 10

A base is a substance that gives up negatively charged hydroxyl ions when dissolved in water; they’re often called alkaline substances. Liquid soap, ammonia, and baking soda are all bases. An acid gives up positively charged hydrogen ions when dissolved in water. Some examples of acids include vinegar, orange, juice, and sulfuric acid.

Question 11

What is the pH scale?

Answer 11

Whether a solution is basic or acidic, it can be measured on a pH scale. the pH scale ranges from 0 to 14, with 0 being the most acidic (that’s where you find battery acid) and 14 being the most basic (that’s where liquid drain cleaner hangs out). Pure water falls right in the middle, at a very neutral 7.

Each whole value below 7 — the most neutral number on the scale — is ten times more than the value after it. That means something with a pH of 3 is 10 times more acidic than something with a pH of 4 and 100 times more acidic than something with a pH of 5.

pH stands for the Latin potentia hydrogenii — in English, potential hydrgone. The scale is based on the logarithm pH = -log(H+), where log is the base 10 logarithm and H+ is the hydrogen ion concentration measured in moles per liter.

Question 12

What is physics?

Answer 12

Physics is the branch of science that delves into matter and energy. It includes mechanics, heat, light, and other radiation. Physicists also study sound, magnetism, electricity, and the makeup and structure of atoms.

Question 13

Scientists around the world need a common language to share and explain their discoveries, so they use SI units of measurement, what are the things that you should know to keep track with the SI units of measurement?

Answer 13

Question 14

Differentiate weight and mass.

Answer 14

Weight is a measure of the force gravity exerts on an object or the force needed to support it. You’re being pulled to the Earth at an accelerating rate of 9.8 meters per second squared, or m/s², but if you were on the moon, you’d be pulled to it at a rate of 1.62 m/s². You weigh less on the moon than you do on Earth.

Mass is a measure of an object’s inertial property — the amount of matter it contains. The mass of an object doesn’t change, whether it’s on the moon, in a compression device, or anywhere else.

Question 15

Differentiate Newton’s three laws of motion & Newton’s law of universal gravitation.

Answer 15

1. Law of inertia - Newton’s first law of motion states that if an abject at rest tends to stay at rest, and an object in motion tends to stay in motion with the same speed and in the same direction, unless acted upon by an unbalanced force or friction.
2. F=ma - Newton’s second law of motion says that when dealing with an object for which all existing forces are not balanced, the acceleration of that object (as produced by the net force) is in the same direction as the net force and directly proportional to the magnitude of the net force, and is inversely proportional to the object’s mass.
3. Action-Reaction - Newton’s third law of motion set-forth that for every action, there is an equal and opposite reaction. That means that when an object exerts a force on another object, the second object exerts an equal force in an opposite direction on the first object.

Newton’s law of universal gravitation portrays that all objects in the universe attract each other with an equal force that varies directly as a product of their masses, and inversely as a square of their distances from each other. This force is known as gravity.

The mathematical equation that Newton’s law of universal gravitation relies on is expressed this way: F_g = G(m₁m₂)/r²

Question 16

To a physicist, a force performs work on an object when it causes the object to move. You can calculate the work performed on an object by multiplying the force by how much the object moves. The equation for work is…

Answer 16

W=Fd, where W represents work, F represents force, and d represents displacement. Units of work are measured in newton-meters (Nm) or joules (J) under the SI system, but under the U.S. system, they’re measured in pounds.

Question 17

Define energy and differentiate kinetic energy and potential energy.

Answer 17

Energy, which is also measured in joules, is the capacity for doing work. it can exist in several forms, such as electrical, chemical, and thermal, but it’s always either kinetic or potential. Kinetic energy is the energy an object possesses because of its motion, and potential energy is the energy an object stores due to its position or configuration. Potential energy turns into kinetic energy when an object begins moving.

Question 18

In physics, what is power?

Answer 18

Power is the rate of doing work or the rate of converting energy per unit of time. You can calculate it with the formula P=W/t, where P represents power, W represents work, and t represents time. Power is measured in watts, and one watt is defined as one joule per second.

Question 19

What are sound waves?

Answer 19

Sound waves are actually fast-moving waves of pressure that result in the vibrations of particles in the medium carrying them (most of the time, that’s air).

Question 20

Echo is technically called…

Answer 20

Sound reflection.

Question 21

What is the sonic boom?

Answer 21

Sound waves travel very quickly. At sea level, they speed through the air at about 760 miles per hour. When you hear about ultra-fast jets breaking the sound barrier, that means jet is accelerating so quickly that it goes faster than the sound waves it’s creating. The result is a sonic boom — a tremendous, explosion-like sound caused by the shock waves the jet makes.

Question 22

Sound is measured in amplitude and wavelength, explain amplitude and wavelength.

Answer 22

Sound waves travel in ripples, like water (that’s why you can hear around corners), and they spread out as they go. The higher the sound’s amplitude is, the more intense — and loud — it is. The higher a sound’s wavelength (the number of sound waves it creates per second) is, the higher its pitch sounds. A violin makes more sound waves per second than a bass guitar does, so its pitch sounds.

Question 23

How is wavelength and frequency related?

Answer 23

Wavelength and frequency are related. The shorter the wavelength, the higher the frequency. Frequency is typically measured in hertz (Hz).

Question 24

The speed light travels are directly impacted by refraction and reflection. It travels faster through empty space (about 186,000 miles per second) and slower when it is passing through water, glass, or other mediums.

Differentiate refraction and reflection.

Answer 24

1. Refraction is the bending of light as it passes from one medium to another. Rainbows, the lenses of your glasses, and magnifying glasses are all possible because of refraction. Light refracts when it travels at an angle from one medium into another, such as from air to water. When the light slows down, it begins traveling at a different angle or in a different direction. The amount that light bends depends on its change in speed and the angle at which it hits the new medium. Rays of light that enter a convex lens, which curves outward, gather together at a focal point on the other side of the lens (like your eyeglasses or a magnifying glass). Concave lenses bend light away from ta focal point and results in a smaller image for the person viewing it — like peepholes, binoculars, telescopes, and your car’s mirrors.
2. Reflection occurs when light bounces off an object. If it bounces off a smooth, shiny surface (such as glass, water, shiny metal, or a mirror), the light reflects at the same angle it hits; that’s called specular reflection and is what you see in the mirror or a smooth, mountain lake. When it reflects off a rough surface, you see diffuse reflection. Most of the things you see are due to diffuse reflection, which occurs when light hits your do, your energy drink can, or this book. Light has reflected off each of those things and traveled in nearly all directions; the light that makes it to your eyes shines on your retina (in the back of your eyes), which passes a signal to your brain.

Question 25

What is heat?

Answer 25

Heat is the flow of energy from warm object to cooler object, and all matter contains heat energy (from volcanoes to ice cubes). Often called thermal energy, it is the result of atoms, molecules, and ions moving in solids, liquids, and gases.

Question 26

What is thermal equilibrium?

Answer 26

A condition in which no heat is flowing between two matters anymore.

Question 27

Heat transfer in three ways… what are those? and differentiate all of three of them.

Answer 27

1. Conduction transfers thermal energy in solids. The moving particle in a warm solid can increase the thermal energy in particles of a cooler solid by directly transferring it, particle by particle. In solids, the particles are closer together, and that makes them better conductors of heat than liquid or gases are. Some materials are really good at conducting heat, like metal, so they are called conductors. Other materials, such as plastic, foam, and wood, aren’t so good at conducting heat, so they’re known as insulators.
2. Convection transfers thermal energy through gases and liquids. The air heats up and gives particles thermal energy, and the particles move faster and farther apart while carrying the heat energy with them. If you’re sitting in a warm room right now, thank convection.
3. Radiation doesn’t require particles to carry thermal energy. Instead, it uses infrared waves, which radiate out in all directions and travel at the speed of light until they hit something else. When the waves hit an object, the object can absorb or reflect the thermal energy they carry.

Question 28

What are the four laws of thermodynamics?

Answer 28

The zeroth law of thermodynamics says that if two systems are in thermal equilibrium with a third system, then they are in thermal equilibrium with each other. Thermal equilibrium means that no heat transfers from one object to another because they’re the same temperature.

the first law of thermodynamics is another version of the law of conservation of energy, which says that energy can be neither created nor destroyed. it can be transferred to other locations, though it can be converted to (and from) other forms of energy. However, the total quantity of energy in the universe always stays the same.

The second law of thermodynamics describes how energy affects matter, as well as the relationships between thermal energy (heat) and other types of energy. It says that the more energy is transferred or transformed, the more it’s wasted. It also says than an isolated system has a tendency into a more disordered state.

The third law of thermodynamics says that achieving a temperature of absolute zero is impossible. Absolute zero is the temperature matter would reach if it contained absolutely no heat enegy.

Question 29

What are the side effects of feeling hot and feeling cold in terms of length?

Answer 29

When substances get hot because their molecules are colliding fast, they expand. When things cool down, they shrink. Sometimes the change in size is so small that you don’t notice it — but sometimes it is huge. One example of this change happens in burning houses. The air inside the house is hot, and its molecules are moving really quickly. The air expands so much that it creates a tremendous pressure, and eventually, the windows explode outward.