Forms of Energy and Energy Conservation - Class IX

$1\ cal=4.2\ J$

Chemical
energy

energy which a body possesses by virtue of being in motion.

Kerosene is the by-product of crude oil, which is a fossil fuel. In fossil fuels, energy is stored in the form of chemical energy, which is converted into heat and light energies when burnt.

Heat is a form of energy.  Heat energy is transferred from one body to another as the result of a difference in temperature.

In a solar cell, solar energy from the Sun is converted into electrical energy. This electrical energy is used by the various electrical appliances.

Hydro-electric power is the process where moving water rotates the turbine. Here potential energy of water converts into kinetic enery of water when waters falls downwards from a height.

Elastic potential energy is Potential energy stored as a result of deformation of an elastic object, such as the stretching of a spring. It is equal to the work done to stretch the spring, which depends upon the spring constant k as well as the distance stretched.

unit of energy is joule.

Change in momentum = F * t. Initial velocity = 180 km/h = 50 m/s. Final velocity = -50 m/s. Change in momentum = m * (vf - vi) = 0.3 kg * (-50 - 50) = -30 kg m/s. Magnitude = 30. t = 30 / 3000 = 0.01 s.

The torch cell makes use of redox reaction to store energy in the form of chemical energy. This chemical energy is then converted to electrical energy and finally to light energy as the bulb glows.

In the case of burning wood, stored chemical energy in the log is released due to heating by other excited atoms. This chemical reaction is called combustion and requires oxygen. Combustion changes the chemical energy into heat and light energy.

An electric heater is an electrical device that converts electrical energy into heat energy. The heating elements inside electric heater is an electrical converter and works on the principle of joule heating. An electric current passing through resistor converts electrical energy into heat energy.

 chemical energy is the potential of a chemical substance to undergo a transformation through a chemical reaction to transform other chemical substances.

chemical energy is the potential of a chemical substance to undergo a transformation through a chemical reaction to transform other chemical substances.

 chemical energy is the potential of a chemical substance to undergo a transformation through a chemical reaction to transform other chemical substances.

Chemical Energy is the energy which is stored in the molecules of matter and holds the particles of molecule together.

A torch uses the energy released by the chemical reaction inside the cell and converts it to light energy by making the bulb  glow.

An electric heater converts electrical energy to heat energy.

The energy released on burning coal, oil, wood or gas is the heat energy.

A vibrating body possesses sound energy. It is sensed by our ears.

When two dry bodies are rubbed together, they get charged due to movement of free electrons from one body to the other body, so they possess electrical energy.

The energy possessed by the fast moving water is called the hydro energy. This energy is used to generate electricity in hydroelectric power stations.

The energy possessed by a magnet due to which it can attract iron filings, is called the magnetic energy.

In the second orbit, $n=2$
$\therefore$ Ionisation energy $E=-\cfrac{13.6}{{(2)}^{2}}$
$=-\cfrac{13.6}{4}=3.4eV$

Energy of an abject due to its position or arrangement in a system is potential energy. 

Gravitational and Elastic Potential Energy are two types of potential energy

Mechanical energy comprises of Potential and Kinetic energy.

Leap energy is not any kind of energy

Potential energy is the energy stored by the virtue of the position of a body.While,kinetic energy is the energy possessed by the virtue of motion.
Hence, K.E is always +ve .
When a body is raised to a particular height,work is done against the force of gravity and P.E is $ - $ve.
When the body is falling freely the work is done in the direction of force of gravity and P.E is $+$ ve.

Only kinetic energy can have positive value. Potential energy has negative value and mechanical energy is combination of these two hence can either be positive or negative.

The kind of energy transformation takes place

The initial potential energy of the ball is proportional to 30 m. Since it loses 40% of its energy upon hitting the ground, it retains 60% of its energy. The rebound height will therefore be 60% of the initial drop height, which is 0.60 * 30 = 18 meters.

Speed is given as constant. Though the velocity is changing only in direction, its magnitude remains the same. Thus the kinetic energy remains constant as it is a scalar quantity but momentum would change as it is a vector quantity.
Also as the elevation of the ball keeps on changing during the motion, the potential energy changes

The bond energy of a DNA molecule is 1 eV, so this will be the energy required to break the bond

$\begin{array}{l} We, , know, , that, \ \Delta E=Q+W \ =600+\left( { -400 } \right)  \ =200J \end{array}$

On microscopic level all energies are either Kinetic or potential as they are either created due to motion or particle interaction.

As raindrops fall, they lose gravitational potential energy, which is converted into kinetic energy (ignoring air resistance for this conceptual question).

Answer is D.

Potential energy is the energy that is stored in an object due to its position relative to some zero position. An object possesses gravitational potential energy if it is positioned at a height above (or below) the zero height.
There is potential energy stored in a water reservoir behind a dam. It is converted to kinetic energy when the water starts flowing down the penstock, from the dam. This kinetic energy is used to turn a turbine.
Hence, the water stored in a dam possesses potential energy.

You'd burn it, just like you might burn coal or oil or natural gas. The stored energy in the wood is chemical energy, meaning that it can be released by a chemical reaction (burning). It's closely related to those fossil fuel energies, because the chemical energy was formed by photosynthesis, using energy from sunlight as the input.

An atomic bomb contains atomic energy which is converted to heat and sound energy.

A body having either. Kinetic' energy or Potential energy or both is said to be having Mechanical energy.

A wound spring has mechanical energy.

the water in dam is stored is standing still, it isn't moving. 

Force has a unit of newton while K.E ,work and potential energy occurs due to some applied force,and their unit is joule.

Water, like many substances, contains two kinds of energy. The first kind of energy is called kinetic energy. This is energy that is used during the execution of processes, such as movement. Because of kinetic energy water can flow and waves can exist.
But water can also contain potential energy. This is energy that is stored in the water. Stored, but not used. This energy can become useful when water starts to flow. It will be transferred to kinetic energy and this will cause movement.
so it is clear that flowing water have kinetic energy .

When kerosene burns its hydrocarbons react with oxygen and produces heat and light energy, so some chemical enwrgy is stored in the kerosene because energy can neither b created nor b destroyed.

When someone climb staircase then he has to do so physical work, so some muscular energy is spemt, also if his relative position wrt earth chamges so some gain in kinetic energy of the body, body was initial at rest amd finaly at rest so no kinetic energy is gained or lost.

In an isolated system only $T.E$ is conserved $M.E$ can not be conserved in case of inelastic collision$.$ Some energy is converted into heat$.$ and sum of $P.E,K.E$ and lost energy remains const$.$

Muscular energy is derived from the chemical energy stored in molecules like ATP, which is released through metabolic processes.

Both potential energy (due to going up against the force of gravity) and kinetic energy (because of movement of the body).

Mechanical energy is the sum of kinetic and potential energy. A swimming fish possesses both kinetic energy (due to motion) and potential energy (due to its position in the water column).

The Energy that gets released when the bonds are formed was stored in the electromagnetic fields inside of the atom. When the bond is formed, the electrons and protons assume a configuration that has an, overall, less intense combination of electric and magnetic fields inside of the bonded atoms than when they were separate. 

Since the body B is in a moving train, it will have higher kinetic energy as compared to the body on platfrom. It is because the speed of the body $A$ is zero.

as the striker is moving it will possess kinetic enegry

Geothermal energy relies on heat from the Earth's interior. Regions over hot spots in the crust, where magma is relatively close to the surface, are ideal for tapping into this heat.

When a dielectric slab of constant K completely fills the space between the plates of a charged disconnected capacitor, the capacitance increases by a factor of K, becoming C equals K times C0. Since the charge remains constant, the stored energy U equals Q squared divided by 2C, which means the new energy becomes the initial energy divided by K.

Work done per lift = mgh = 10 * 9.8 * 0.5 = 49 J. Total work for 1000 lifts = 49,000 J. With 20% efficiency, energy required from fat = 49,000 / 0.20 = 245,000 J. Fat energy density = 3.8 * 10^7 J/kg. Mass of fat = 245,000 / (3.8 * 10^7) = 6.447 * 10^-3 kg.

Potential  to kinetic energy