Category: Physics Notes PPT

Mass is a scalar quantity which is mostly dependent on the inertia. Inertia is the resistance of an object to change its state of motion whenever an external force is applied to it. Therefore, an object with greater mass has a high tendency to resist acceleration. The mass of an object helps to know how heavy the object is without gravity. It is constant because the mass remains the same at different places at a given moment. Density and volume are intrinsic characteristics of matters. In simple words, anything that has mass and occupies space also has volume and density. To understand the relationship between density and volume, one has to have a prior understanding of matter. Density can be said as the  amount of mass present in a substance for a given volume. Density is the relationship between mass and volume. We can know from the density how tightly the molecules of an object are packed in the available space. The density of the object never changes with  size and shape. 

But the density can be changed depending on the  temperature and pressure applied to the object which further results in the  change in substance. Volume is a  physical quantity that is derived from quantity and expresses the three dimensional extent of an object which is calculated using the SI unit. Example, the volume of a cube is equal to side times side times side. As the side of a square is the same, we can take the length of one side cube. Furthermore, an understanding of density and volume as general terms is also essential. Herein, volume is the physical space occupied in three dimensions by a matter, while density is the mass per unit of volume. 

The volume of a substance is three dimensional. It is taken as length in three directions unlike area or length, and the volume of the substance.The standard unit used to measure volume is metre. The unit is converted into bigger and smaller units like a decimeter or kilometre based on how big or small the quantity is, it is done by simply dividing/ multiplying by tens, hundreds, thousands, and so on. The density of any object is defined as the mass of that object per unit volume. Density helps to determine how close or far away the molecules are packed in a given space. The very famous scientist known as Archimedes discovered the concept of the Density of an object. In the metric system, Density is measured in kg/m3 and is represented as D or ρ. The density of a substance does not change under some constant conditions without depending on the amount. Mass depends on the amount because we cannot define the mass of a substance without knowing its volume and other environmental conditions.  There is a lot of difference between mass and density under different conditions and different elements and compounds. Hydrogen is the lightest atom and has one quarter the mass of helium which is the second lightest. Hydrogen atoms join together to form one molecule but one molecule of hydrogen weighs on half as much as one single helium atom. Due to the nature of the gas, some amount of hydrogen gas is about half of the density of helium gas under similar conditions. But, in solids and liquids the relationship of density is more complex. The atomic or molecular constituents come together and the density changes depending on the size and shape of the bond.

What is the Relation between Density and Volume?

The density and volume relation states that both are proportional to each other. It means that even a slight change in density is likely to cause a change in volume of that specific matter, be it an element or a compound.

Similarly, the reverse is also valid, wherein even a slight change in volume will lead to a change in density of a specific object. Alongside, you should also be familiar with the sign conventions for every parameter so as to represent the relationship in mathematical terms easily. 

The mathematical expression for the relation between mass volume and density is given below –

⍴ = M/V

Where ⍴ (read rho) = density 

M = mass, and

V = volume

Furthermore, as a student you should also note the units of both density and volume too. Consequently, as volume is a three-dimensional quantity, it has its unit in a cubic format, such as a cubic metre. 

In the case of density, which is defined as the rate of change of mass per volume, the unit is kg/cubic metre and its likes. The unit for mass can be kilograms or grams, depending on SI and CGS units, whichever is applicable. Hence, students should be careful while establishing a relationship between mass volume and density and also while converting from one unit to another.

Most features are studied by the scientists. They may be measured in phases of 1 or greater of four properties: duration, time, mass, and electric powered charge. The quantity of a dice is a unit of duration cubed which means the duration can be increased by using width and then it is increased by using height. Volume is measured in terms of duration and it is described as the quantity of three dimensional area that an item occupies. Volume is measured in cubic metres, for example cubic centimetres. There are 1000 millilitres in one litre. Density is measured as the ratio of mass and density. Density is also taken as a quantity that tells the available space inside an area. The unit of density is g/cm3. Mass is difficult to find. Density is found in terms of mass and volume. Volume is stable and it is described as the space occupied by a substance. The size of the substance is different in different situations. The volume of a dice can be calculated by multiplying height and width. There are different ways of calculating volume of different objects.

Points to Remember

The relation between volume and density with mass has some key points that students should understand for explicit knowledge of the same. The points are listed below –

• Any two matter having the same volume may not have the same density.

• Any two matter having the same mass may not be equal in volume. 

• Water is an exception in this phenomenon, as it increases in volume while freezing, thereby having more volume in its solid state than that of its liquid state. This process begins at 4°C and is known as anomalous expansion of water.

• Water is used as a reference for gauging density of other matters. 

• Cool air is denser than warm air.
  

While studying the relation between density volume and mass, students should note here that the density of water changes at different temperatures. Nonetheless, its density at 100 degrees Celsius is considered the basis of reference. 

It would be best if you would also look into the conversion of density to volume and vice versa to develop an understanding of advanced numerical. Make sure you are able to convert them easily, for which you should memorise the basic formula for density.

For a piece of more detailed information on the mass volume and density and their related features, conversions and applications, go through our online learning programmes. They have the top-notch study materials drafted by our subject experts for your clarification. 

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Energy must be transferred to an object to help it move, and the energy can be transferred in the form of force. The energy transferred by force to move any object is known as work or work done. Therefore, work and energy have a direct relationship. The difference in the kinetic energy of an object is called work done by the object. Work and energy are common terms in Physics and can be considered two sides of a coin. This article is necessary to state the relationship between work and energy.

What is Work and Energy ?

Work

When a force causes motion, work is said to done. A person climbing a flight of stairs is an illustration of this. Because he is moving against the force of gravity, the person has done work in this case. Any force’s work is influenced by a number of factors. The distance the body moves in the direction of the force is one of the elements. The force is the second factor. Work is defined as the product of a body’s displacement and force in the direction of the force. Work equals F*S, where F stands for force and S stands for distance. Work is equal to FS Cosθ when a body is displaced by a distance with a force operating on it.

Work = force × displacement towards the force

Energy

When you play for a long term or do quite a little physical work at your own home or out of doors you get tired, i.e., your body indicates unwillingness or reluctance towards similar play or work. at the moment you could also experience hunger. After taking a rest for some time or/ and eating something you may once more be ready for work. How does one provide an explanation for those experiences? In reality, when you do work, you expend strength and extra energy is needed to do extra work. The capability of a body to do work is decided by the energy possessed with the aid of it. i.e., 

The energy possessed with the aid of a body = overall work that the body can do. Energy has the same unit as work, i.e., joule denoted by means of J. however, conversion of 100% of energy might not usually be doable, because, within the process of conversion of energy into work a few energy may additionally remain unused or can be wasted. 

Relation between Work and Energy

The capacity to do work is referred as energy. This refers to the force that one thing will put on another object in order to displace it and cause a change in its location. Work is defined as the action of displacing an object by exerting a particular amount of force on it. One would expect a shift in position as a result of doing so. The rate at which work is completed or the amount of work completed per unit of time is referred to as power.

Based on these criteria, it is safe to conclude that energy is a fundamental requirement for completing work. The amount of work completed in a given time period is referred to as power. Work, on the other hand, is the action required to change the object’s location. To do work, you require energy, and power is the rate at which you can do work, whereas energy is the capacity to accomplish work.

Work and energy are related to each other i.e, with an increase in work results increase in energy, or vice versa. Work done can be explained mathematically by:

[W = frac{1}{2}mv^{2}_{f} – frac{1}{2}mv^{2}_{i}]

in which,

• W is the work achieved through an object in terms of Joules.

• m is the mass of the object measured in terms  of kilograms.

• vi is the initial velocity in  m/s. 

• Vf is the final velocity of an object measured by the usage of m/s.

Hence, the work-energy theorem states that total work done by the net force on an object is equal to change in its kinetic strength.

The word “mass” has two implications in special relativity: invariant mass (likewise called the rest mass) that is similar for all observers in all reference frames; while the relativistic mass is reliant on the velocity of the observer. As indicated by the idea of mass-energy relativity, invariant mass is identical to rest energy, while relativistic mass is identical to relativistic energy. 

The expression “relativistic mass” tends not to be utilized in particle and nuclear physics. It is the mass of the body that changes with the change in the body’s speed as its speed approaches the speed of light, i.e., 3 × 108 m/s.

What Will You Learn Here?

This page will discuss the mass of light, a relativistic mass, relativistic speed, rest mass formula, and the relativistic mass formula.

Rest Mass

According to the theory of special relativity, the rest mass is called the invariant mass that remains invariant for all the observers in various frames of reference. The invariant mass is another name for the rest mass of particles inside the system. In contrast, the rest mass is preferred over the rest energy (E). 

Hence, invariant mass is a characteristic unit of mass utilized for systems that are being seen from their focal point/centre of mass (COM frame). 

Point To Note:

The idea of invariant mass doesn’t need bound systems of particles. In such a case, it might likewise be applied to systems of unbound particles in high-speed relative motion. 

Along these lines, it is regularly utilized in particle physics for systems that comprise broadly isolated high-energy particles. 

Assuming such frameworks were obtained from a solitary particle, the calculation of the invariant mass of such frameworks, which is a never-changing quantity, will give the rest mass of the parent particle (since it is preserved over a long period).

Rest Mass Formula

It is helpful in computation that the invariant mass of a system is the total energy of the system divided by c2 in the COM frame (where, by definition, the momentum of the system is zero).

The rest mass is denoted by mo.

So,  the rest mass formula is:

mo  = E/c2

Rest Mass is a Conserved Mass

The invariant mass of any system is likewise a similar quantity in every single inertial frame, it is a quantity determined from the total energy in the COM frame. 

Following the calculation of the rest mass in the aforementioned method, the rest mass is also used to compute system energies and momenta in other frames where the momenta are not zero, where the total energy will fundamentally be unexpectedly different as compared to the COM frame.

Similarly, as with energy and momentum, the invariant mass of a system (having multiple particles) can’t be varied or changed, and it is in this manner monitored that the rest mass of the system cannot be destroyed or changed; thus, it remains conserved, as long as the system is not prone to all influences.

Relativistic Mass

From the above text, we understand that relativistic mass is studied under Einstein’s special theory of relativity. It is a mass that is associated with the body in motion.

Mass, in physics, is a quantitative proportion of idleness/inertia, an essential property of all matter. It is, as a result, the obstruction that a body of matter offers to an adjustment of its speed or position upon the action of force.

The quantifiable inertia and the distortion of spacetime by a body in a given frame of reference are controlled by its relativistic mass.

Relativistic Speed

Relativistic speed is the speed at which relativistic impacts become important to the ideal exactness of estimation of the phenomenon being noticed.

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Do You Know?

When any closed system (for instance a container of hot gas) is measured, which necessitates that the estimation is taken in the center of the momentum frame where the system has no net energy. In such a case, the invariant mass becomes equal to the relativistic mass, which is the total energy of the system divided by c2.

So, the relativistic mass is the sum total quantity of energy in a body/system divided by c2. 

Mathematically, the relativistic mass formula is:

E = mREL c2

For a particle possessing finite rest mass “mo” moving at a speed “v”, i.e., relative to the observer, one finds the following relativistic mass formula:

 mREL  =  [frac{m_{0}}{sqrt{1-frac{v^{2}}{c^{2}}}}]

Where,

 mREL   = mass of an object in motion

 mo   = rest mass

Point To Note:

In the center of the momentum frame, the speed “v = 0”, and the relativistic mass equals the rest mass, while in other frames, the relativistic mass of a body or system of bodies includes a contribution from the “total” kinetic energy of the body, i.e., the kinetic energy of the center of mass of the body, and is larger the faster the body/system of bodies move. 

Therefore, unlike the invariant mass, the relativistic mass relies on the frame of reference of the observer. 

However, for a given single frame of reference and isolated systems, the relativistic mass also remains a conserved quantity. The relativistic mass is also the proportionality factor between velocity and momentum, which is given as per Newton’s second law of motion:

P   =  mRELv 

Fun Fact

Do You Know What the Mass of Light is?

Well! Light is a bundle of photons. Photons (mass of light) have  “mo = 0, “ i.e., zero rest mass; however, they do contribute to the inertia and possess weight in a gravitational field of any system comprising them.

You often do not acknowledge several physical, chemical and other changes happening around you. Some of these processes cannot even be felt, with their existence often eluding you. However, these processes do occur and there is a difference in the state of the participants taking part in these processes. 

For instance, boiling of water, melting of ice, burning of things, etc. All these are processes that are distinct in nature, although, in all of them, one aspect is common. There is an exchange of heat or energy in each case, and they can be classified under reversible and irreversible processes. 

What is a Reversible Process?

A reversible process is the process where  it never occurs; on the contrary the irreversible process is the one which can be said to be the natural process and cannot be reversed.

For example water changing into water vapor is a reversible process whereas tearing the page is an irreversible process. This is because can we tear the pages? No we cannot so the process cannot be reversed.

Thermodynamics is the example of the reversible process. Here the system and the surroundings return to the same stage at the end of the process.

Students should note that a reversible process takes two processes into account. While in the first process participants convert into another form, in the case of this second process the reverse reaction takes place where the resultants get back to the initial stage.

Hence, understanding this will help in further delving into the difference between reversible and irreversible processes. You should also note that understanding these processes is not just vital for your Physics curriculum, but also that of chemistry.

Types of Reversible Processes

There are two types of reversible processes. The internally reversible process and the external reversible process.

In other words we can define a reversible process in simple words that the process that can be reversed completely.

What is an Irreversible Process?

To understand this, consider a reversible process example – the cooking of food. You begin by arranging the necessary ingredients – vegetables, spices and meat and cook the entire thing and prepare a dish. Now, however hard you try, you cannot get back the ingredients in their original form. Another fine example is that of fuel consumption where once converted into energy, the process cannot be reversed to get back the fuel.

They have already been turned into something new which possess a completely different set of properties. Yet another crucial aspect that comes here is that the participants lose their individual characteristics in an irreversible process. 

Therefore, students should be cautious while studying both reversible processes and irreversible processes. Each process or method should be carefully analyzed so as to understand its type. 

Reversible and Irreversible Process in Thermodynamics

In terms of thermodynamics, a reversible process is where the participants go back to its initial form by inculcating minor or negligible changes in their surroundings. Contrarily, an irreversible process is a naturally occurring phenomenon, which does not go back to its original state. 

Students should be able to tell the difference between reversible and irreversible processes in thermodynamics only when they have built an understanding of the same. 

Factors behind Irreversibility of a Process

A reversible process has certain consciousness if the procedure has to be undergone.

On the other hand, an irreversible process can be said to be the thermodynamics process that departs equilibrium.

When we talk in terms of pressure we can say that it occurs when the pressure of the system changes and the volume does not have time to reach equilibrium.

One of the points to note is that the system and the surrounding does not come back to the original state even after the completion of the process in the spontaneous process.

The Reversible Nature of a Process is Dependent on Multiple Factors Such as –

As a student, it is important you have an idea of the various criteria for reversible and irreversible processes. 

To know more about what is a reversible and irreversible process, check our online learning programmes for an in-depth understanding. You will get access to high quality lessons that will help you in building these vital concepts from their grassroot level.

You can even get your learning materials on our app where we explain reversible and irreversible processes and every other necessary concept in the most detailed manner.

The term ‘satellite’ refers to a natural object such as a moon or spacecraft which is an artificial satellite orbiting a larger astronomical body. Most of the known natural satellites orbit planets, the Earth’s Moon is the most obvious example of it.

All the planets in the solar system generally except Venus and Mercury have natural satellites. More than 160 such objects have so far been discovered in the solar system with Saturn and Jupiter together contributing about two-thirds of the total. 

The planets’ natural satellites vary greatly in size and shape as well as colour. A few satellites are larger than Mercury, for example, the planet Saturn’s Titan and Jupiter’s Ganymede each of which is more than 5,000 km that is about 3,100 miles in diameter. 

The satellites also usually differ significantly in composition. The satellite moon for example generally consists almost entirely of rocky material. On the other hand, we see that the composition of Saturn’s Enceladus is 50 percent or more ice. Some asteroids are said to have their own tiny moons.

Natural and Artificial Satellites

A natural satellite is a moon that orbits a planet or a star. For example, the moon is a satellite because it orbits the earth. Usually, the word that is “satellite” refers to a machine that is launched into space and moves around the planet Earth or another body in space.

The planet Earth and the satellite moon are examples of natural satellites. There are thousands of artificial or man-made satellites that are orbiting Earth. 

In the context of spaceflight, a satellite is said to be an object that has been intentionally placed into orbit. These objects are known as artificial satellites to distinguish them from natural satellites such as planet Earth’s Moon.

Some satellites take pictures of the planet earth that helps meteorologists predict weather and track hurricanes. Some of the satellites take pictures of other planets, the sun and the black holes and the dark matter or faraway galaxies. These pictures generally help scientists to understand the solar system and the universe as well.

Still, we can say that the other satellites are used mainly for communications such as beaming TV signals and phone calls that are around the world. A group of more than 20 satellites make up the Global Positioning System or the GPS. If we have a GPS receiver, these satellites can help figure out our exact location.

Satellite Composition

The satellites come in many sizes and shapes. But most have at least two parts in common – that is a power source and antenna. The antenna usually receives and sends information which is often to and from Earth. The power source can be a panel or solar panel or battery. Solar panels generally make power by turning sunlight into electricity.

Many satellites of NASA  carry cameras and scientific sensors. Sometimes these instruments usually point toward the planet Earth to gather information about its land, air and water. Other times they face toward space to collect data from the universe and the solar system.

Satellite Uses

Satellites can collect more data, more quickly than instruments present on the ground.

The satellites also can see into space better than telescopes at planet Earth’s surface. This is because satellites usually fly above the clouds and the dust and molecules in the atmosphere that can block the view from ground level.

Before satellites TV signals didn’t go very far. The TV signals only travel in line which is straight. So they would quickly trail off into space instead of following the Earth’s curve. Mountains or tall buildings would block them. Phone calls to places which are faraway were also a problem. The setting up of wires of telephone over long distances or underwater is difficult and costs a lot.

With satellites, the signals of TV and phone calls are sent upward to a satellite. Then almost instantly the satellite can send them back down to different locations on Earth.

Satellites Launched into Space 

On 4 October 1957, the Soviet Union Russia launched the world’s first artificial satellite named Sputnik 1. Since then there are 8,900 satellites from more than 40 countries have been launched. According to the estimates of 2018, there are some 5,000 remaining in orbit. Of those who are about 1,900 were operational while the rest have exceeded their useful lives and become debris space. 

In terms of countries with the most satellites, the country USA has the most with 859 satellites. China is said to be the second with 250 and Russia third with 146. These are then followed by India at 118, Japan at 72 and the UK at 52. 

A few large stations of space including the International Space Station has been launched in parts and then it is assembled in orbit. Over a dozen probes of space have been placed into orbit around other bodies and become artificial satellites of the Moon, and Mercury, Venus, Mars, Jupiter, Saturn, a few asteroids, a comet and the Sun.

One can describe sea breeze as a wind system that is localized. The sea breeze definition can be stated as the characteristic wind flow that takes place from sea to land, usually during the day. It is also called the onshore breeze. To describe sea breeze formation we have to focus on the pressure difference which is created by different heat capacities of water and lands that are dry. Apart from the sea breeze, a land breeze is also observed. Sea breeze usually moves from large bodies of water towards landmasses. The difference between the sea breeze and the prevailing winds is that the sea breeze is more localized.

What is Sea Breeze?

To understand what is sea breeze, we first have to understand how breezes are formed. Breeze is usually described as a moderate air current. It is gentle and light. The temperature gradient of any type results in the formation of a breeze. Breezes of two types- sea breeze and land breeze. They vary information and also their direction of flow. The sea breeze definition says that sea breeze is a type of wind that flows from the inland of the ocean to the landmass. Since this breeze originates in water bodies, thus it is called sea breeze.

Sea Breeze – Origin and Characteristics

We all know that during the daytime the ocean and the land both get heated up. Now since water absorbs heat better than landmass, water absorbs heat much more slowly than land. As a result, the air above the land gets heated up quickly during the daytime. The phenomenon involved in this heating is called convection. Now as the air above the land gets heated up during the daytime, it starts expanding. As the air above the land expands it becomes less dense. The air above the land now has lesser pressure compared to the air above the waterbody. Now air starts flowing from a region of higher pressure to a region of lower pressure. This is how does sea breeze occur when the air starts flowing from the waterbody toward the landmass.

Sea breeze occurs during the daytime. During spring and the months of summer is the time when does sea breeze occur mostly. The sea breeze can be very soothing. People who live near the coast can experience this gentle breeze. Usually, people who live within a 30-40km distance of the coast experience winds during the daytime with a speed of 10 to 20km per hour which are caused due to sea breeze.

Sea Breeze and Land Breeze Activity

The sea breeze and land breeze activity differ in origin, movement and time of formation. Sea breeze occurs during daytime and land breeze occurs during the night. Sea breeze originates over the water body whereas land breeze occurs over the landmass. Landmass loses heat more quickly than waterbody. As a result, soon after sunset the sea breeze dies away and the land breeze is formed. Land breeze is also called offshore breeze. At night, the pressure over the land is higher than the pressure over the waterbody. As a result, now wind flows from the land towards the waterbody.

Did You Know?

1. The nature and strength of the sea breeze bear a direct relationship with the temperature difference between landmass and waterbody. The temperature difference between landmass and waterbody results in a pressure difference due to the expansion of the air layer. Sea breeze mostly occurs in the spring and summer months. This is because during this time the temperature difference is maximum due to unequal heating from sun rays in the afternoon. 

2. To describe sea breeze, we can say that these breezes are moderate. They are gentle. They bring fair weather. The fair weather is often accompanied by drizzles. However, from the sea breeze definition, it can also be inferred that due to the presence of strong winds which flow offshore. Strong winds with a speed of more than 15km/h can subdue the effect of sea breeze.

Conclusion

In the coastal region, it is seen that sea breezes generally alternate with land breezes. This takes place largely in absence of strong winds. This is supported by strong heating during the daytime and strong cooling is needed during nighttime. It is observed that a low-level convergence of air is produced as the sea breeze and its surface flow gets terminated over land. This kind of convergence results in the development and formation of clouds. Such formation of clouds results in rainfall during the daytime.