author

Rajkumar Yadav

teacher | Maths Chemistry

Description

Hi, I am Raj Kumar Yadav from BHU.

Qualification

M.Sc

Experience

1-3 Years

Teaching Classes

9-10

Current Organization

Hindu Public School

Kinetic Energy

Kinetic energy is the energy an object has because of its motion.

 

For acceleration of any object, we need to apply a force. After work done by applying force, energy will get transfer to the object, and the object will be moving with a new constant speed. The energy transferred is known as kinetic energy, and it depends on the mass and speed achieved.

 

Kinetic energy can be transferred between objects and transformed into other kinds of energy.

How we calculate KE

Consider a box of mass m being pushed through a distance d along a surface by a force parallel to that surface.

 

 

we know that we can substitute the acceleration if we know the initial & final velocity and the distance.

So, when a net amount of work is done on an object, the quantity which we call kinetic energy K changes.

 

 

Alternatively, one can say that the change in kinetic energy is equal to the net work done on an object or system.

 

Reflection and Refraction of Light

Reflection of light

 

Reflection of light is the change in direction of light back in the same medium when light strikes it after putting on a smooth surface light mirror or others.

 

Laws of Reflection

 

1. The angle of incidence is always equal to angle of reflection, i=r.

2. The incident ray, reflected ray and the normal to the reflecting surface at the point of incidence lie in the same plane.

 

Image formed by Plane Mirror

 

·         The size of image is equal to that of object.

·         The image formed is as far behind the mirror as the object is in front of it.

 

Reflection of light by spherical Mirrors

 

Mirrors, whose reflecting surface are curved inward or outward spherically are called spherical mirror.

·         If it is curved inward, It will act as concave mirror

·         If it is curved outward, It will act as a convex mirror.

 

 

Refraction of Light

 

Refraction is the bending of light as it passes from one transparent substance into another. It also happens with sound, water and other waves.

Kepler's laws of planetary motion

Kepler’s Law states that the planets move around the sun in elliptical orbits with the sun at one focus. There are three different Kepler’s Laws of Orbits, Areas, and Periods.

 

Laws of Orbits: The Planets move around the sun in elliptical orbits with the sun at one focus.

The orbit of any planet is an ellipse around the Sun with Sun at one of the two foci of an ellipse. But according to Kepler, he said that it is true that planets revolve around the Sun, but not in a circular orbit but it revolves around an ellipse.

 

Laws of Areas: The line joining a planet to the Sun sweeps out equal areas in equal interval of time.

The line joining a planet to the Sun sweeps out equal areas in equal interval of time. The rate of change of area with time will be constant.

 

Laws of Periods: The square of the time period of the planet is directly proportional to the cube of the semi major axis of its orbit.

The square of the time period of the planet is directly proportional to the cube of the semi major axis of its orbit.

Avogadro's Law

Avogadro's law is an experimental gas law relating the volume of a gas to the amount of substance of gas present. The law is approximately valid for real gases at sufficiently low pressures and high temperatures.

 

Avogadro's law states that, "equal volumes of all gases, at the same temperature and pressure, have the same number of molecules."

 

For a given mass of an ideal gas, the volume and amount (moles) of the gas are directly proportional if the temperature and pressure are constant.

 

Scientific form of Avogadro’s Law is : V ÷ n = k , this means that the volume amount fraction will always be the same value if the pressure and temperature remain constant.

 

The container holding the gas is flexible in some way and can expand or contract because the volume is one of the variables.

 

  1. If the amount of gas in a container is amplified, the volume upsurges.

  2. If the quantity of gas in a container is reduced, the volume declines.

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