Why?

It is the form of energy which provides heat and power to operate a machine

Electricity is the flow of electrical power or charge

Don't use copy paste system plz

Circuit, cell, bulb, switch... Find out about the electrical terminology your primary-school child will be using in the classroom and try some hands-on activities to support learning about electricity at home. 

Electricity can be created in a variety of ways such as:

• burning fossil fuels (oil, gas, coal) at power stations,
• using wind power generated by wind turbines,
• using solar power generated by the sun,
• using water power (sometimes called hydropower) generated by running or falling water.

Electricity is transported to our homes, schools and places of work through wires and cables.

Electricity can also be stored in batteries (sometimes called cells). 

Ordered paired is a set in which the arrangement of any number or alphabet in accenting order

A pair of numbers in a specific order . For ex- (1,2) , (-4,12)

A derive force is a force which is either calculated using a mathematical process like using formulas and equations. It is a function of other more fundamental physical quantities.

?? Yogita

The forces which we see in our day to day life like muscular, friction, forces due to compression and elongation of springs and strings, fluid and gas pressure, electric, magnetic, interatomic and intermolecular forces are derived forces as their originations are due to a few fundamental forces in nature.

The coefficient of restitution (COR), also denoted by (e), is the ratio of the final to initial relative velocity between two objects after they collide. It normally ranges from 0 to 1 where 1 would be a perfectly elastic collision. The coefficient of restitution depends to a large extent on the nature of the two materials of which the colliding objects are made. It is also affected by the impact velocity, the shape and size of the colliding objects, the location on the colliding objects at which the collision occurs, and their temperatures.

m(12at^2-6bt)

From v=u+at,v_1​=0+at_1​

∴a = v_1​​/t₁​

F=ma=mv_1​​/t₁​​

Velocity acquired in t sec=at=v_1​​/t₁​ ​​t

Power=F×v= ​mv_1​​/t₁​ ×v_1​​/t₁​ ​t​=​mv₁²/ t₁²​t​

Bro contact no do na plz name ke sath

Supplementary units are the dimensionless units that are used along with the base units to form derived units in the International system. The class of supplementary contains only two purely geometrical units, that is the radian and the steradian.

Photons are electrically neutral. Photons have no mass, but they have energy E = hf = hc/λ. Here h = 6.626*10-34 Js is a universal constant called Planck's constant. The energy of each photon is inversely proportional to the wavelength of the associated EM wave. The energy associated with a single photon is given by E = h ν , where E is the energy (SI units of J), h is Planck's constant (h = 6.626 x 10–34 J s), and ν is the frequency of the radiation (SI units of s–1 or Hertz, Hz) 

2x/1+x^2

The inherent property of a material body by virtue of which it cannot change, by itself , its state of rest or of uniform motion in a straight line is called Inertia. DIFFERENT TYPES OF INERTIA:- 1) Inertia of rest - The tendency of a body to remain in its position of rest is called Inertia of rest. Example : A person standing in a bus falls backwards when the bus suddenly starts moving forward. When the bus moves , the lower part of his body begin to move along with the bus while the upper part of the body continue to remain in rest due to Inertia of rest. That is why , a person falls backwards when the bus starts. 2) Inertia of motion - The tendency of a body to remain in the state of uniform motion in a straight line is called Inertia of motion. Example : When a bus suddenly stops, a person sitting in it falls forward. As the bus stops, the lower part of his body comes to rest along with the bus while the upper part of the body continue to remain in the motion due to Inertia and fall forward. 3) Inertia of direction - The inability of the body to change by itself its direction of motion is called Inertia of direction. Example : When a bus takes a sharp turn, a person sitting in the bus experience a force acting away from the centre of the curved path due to his tendency to move in the original direction. He has to hold on a support to prevent himself from swaying away in the turning bus.

The tendency of a body to continue in its state of motion is called inertia of motion .
Example: Rider Falls forwards when a galloping horse stop suddenly. When the horse stops, the Rider on account of inertia of motion, continues moving and hence falls in forward direction.

Following are the different methods that are used for reducing the friction:

• For objects that move in fluids such as boats, planes, cars, etc, the shape of their body is streamlined in order to reduce the friction between the body of the objects as the fluid.
• By polishing the surface, as polishing makes the surface smooth and friction can be reduced.
• Using lubricants such as oil or grease can reduce the friction between the surfaces.
• When objects are rolled over the surface, the friction between the rolled object and surface can be reduced by using ball bearings

Angle of Friction beween any two surface in contact is defined as the angle which the resultant

of the force of limiting friction F_lim and normal reaction N makes with the direction of normal reaction N
as shown in figure. It is marked in the figure as θ.

The value of angle of friction depends on the material and nature of surfaces in contact. 

It can be seen from figure, tanθ = AC/OA = F_lim / N = μ , where μ is coefficient of limiting friction

The angle of repose or angle of sliding  α is defined as the minimum angle of inclination of a plane

with the horizontal such that a body placed on the plane just begins to slide down.

Its value depends on the material and nature of the surface in contact. 

from the figure it can be seen that, f =mg sinα ...............(1)

                                                        N = mg cosα ....................(2)

hence we get,  f / N = tan α = μ  

Frictional force causes a lot of losses in general upkeep and wear and tear of machinery. Hence it is considered as a evil. But almost all crucial tasks cannot be carried out without the presence of friction. Basic activities like walking and writing on a surface are possible due to friction. Hence it is considered as a necessary evil .

When a vehicle goes round a curved road, it requires some centripetal force. While rounding the curve, the wheels of the vehicle have a tendency to leave the curved path and regain the straight line path. Force of friction between wheels and the roads opposes this tendency of the wheels.

In this system, length is measured in centimeter, weight is measured in gram, and time is measured in seconds. MKS System: MKS stands for meter, kilogram and seconds.

Any mechanical quantity can be expressed in terms of three fundamental quantities, mass, length and time. For example, speed is a length divided by time. Force is mass times acceleration, and is therefore a mass times a distance divided by the square of a time. CGS System: It stands for centimeter, gram and seconds. In this system, length is measured in centimeter, weight is measured in gram, and time is measured in seconds. MKS System: MKS stands for meter, kilogram and seconds. Here, length is measured in meter, weight in kilogram and time in seconds.

 

 

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Types of Errors- Systematic Errors

Errors which can either be positive or negative are called Systematic errors. They are of following types:

1. Instrument errors: These arise from imperfect design or calibration error in the instrument. Worn off scale, zero error in a weighing scale are some examples of instrument errors.
2. Imperfections in experimental techniques: If the technique is not accurate (for example measuring temperature of human body by placing thermometer under armpit resulting in lower temperature than actual) and due to the external conditions like temperature, wind, humidity, these kinds of errors occur.
3. Personal errors: Errors occurring due to human carelessness, lack of proper setting, taking down incorrect reading are called personal errors.

Electric and magnetic fields fluctuating together can form a propagating wave, appropriately called an electromagnetic wave.

• Equation of plane progressive electromagnetic wave

E = E₀ sin ω (t – x/c)

B = B₀ sin ω (t – x/c)

Here, ω = 2πf

net force acting on the body will be the resultant of 8N and 6N u can find the resultant by using parallelogram law and once u got the force and u r already provided with mass by using formula f=ma u can find acceleration

Free Fall The motion of falling objects is the simplest and most common example of motion with changing velocity. If a coin and a piece of paper are simultaneously dropped side by side, the paper takes much longer to hit the ground. However, if you crumple the paper into a compact ball and drop the items again, it will look like both the coin and the paper hit the floor simultaneously. This is because the amount of force acting on an object is a function of not only its mass, but also area. Free fall is the motion of a body where its weight is the only force acting on an object.  Free Fall: This clip shows an object in free fall. Galileo also observed this phenomena and realized that it disagreed with the Aristotle principle that heavier items fall more quickly. Galileo then hypothesized that there is an upward force exerted by air in addition to the downward force of gravity. If air resistance and friction are negligible, then in a given location (because gravity changes with location), all objects fall toward the center of Earth with the same constant acceleration, independent of their mass, that constant acceleration is gravity. Air resistance opposes the motion of an object through the air, while friction opposes motion between objects and the medium through which they are traveling. The acceleration of free-falling objects is referred to as the acceleration due to gravity gg. As we said earlier, gravity varies depending on location and altitude on Earth (or any other planet), but the average acceleration due to gravity on Earth is 9.8 ms2ms2. This value is also often expressed as a negative acceleration in mathematical calculations due to the downward direction of gravity. Equations The best way to see the basic features of motion involving gravity is to start by considering straight up and down motion with no air resistance or friction. This means that if the object is dropped, we know the initial velocity is zero. Once the object is in motion, the object is in free-fall. Under these circumstances, the motion is one-dimensional and has constant acceleration, gg. The kinematic equations for objects experiencing free fall are: v=v0−gty=y0+v0t−12gt2v2=v20−2g(y−y0),v=v0−gty=y0+v0t−12gt2v2=v02−2g(y−y0), where v=velocity, g=gravity, t=time, and y=vertical displacement.

Example or exercises