Law of conservation of energy – Grade 7 Science Worksheets

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Law of conservation of energy – Grade 7 Science Worksheets

What is the Law of conservation of energy in chemistry?

Energy can never be created nor destroyed it just changes form.

The law of conservation of energy explains that the total energy in a closed system remains constant it remains to be constant over a period of time.

law of conservation of energy

 In a chemical reaction the motion of individual atoms is governed by the law of conservation of energy. In a closed system, a system that is separate from its surroundings, the total energy of the system always remains constant, even if any physical or chemical change happens.

Conservation of energy is the term used to understand change in energy from one form to another.

What is an example of the law of conservation of energy?

Burning Candle – Chemical energy—Heat energy/Light energy

Burning Candle – Chemical energy—Heat energy/Light energy

Light Bulb – Electrical energy – Heat/light energy

Law of conservation of energy

Stove heater —thermal energy—Heat energy/radiant energy

Law of conservation of energy

A Flow Chart to Describe Law of Conservation Of Energy

Law of conservation of energy

Energy transformation

Kinetic energy —- Potential energy —- Kinetic Energy

When a ball is on the ground its velocity is zero.

And its height above the ground is also zero.

Hence the mechanical energy of the whole system is zero.

Now when the ball is thrown up its initial velocity is high and its height above the ground is less.


As the ball is thrown into the sky the speed of the ball falls and also its distance from the earth becomes more that is its height above the ground increases.

But eventually the ball loses its speed and there comes a point where its speed is zero and height is highest.

After this the law of gravity acts on the ball and it starts to fall but now unlike the upward journey the ball gains speed and height becomes lesser.

The ball is constantly changing in the form of energy it contains as it possesses high kinetic energy at the beginning when thrown and finally possesses zero potential energy.

The ball gets kinetically charged as it moves higher later potentially charged.

The ball possesses full potential energy at its highest point, which changes to kinetic energy as it falls to the ground.

As it falls to the ground vice versa happens potential energy converts to kinetic energy.

Kinetic energy is always lost as an object travels upward against the force of gravity and as it loses kinetic energy the object gains potential energy, which in turn converts into kinetic energy as the body falls downward on the Earth.


Check Point

A. Fill in the blanks –

  1. The law of conservation of energy states that the ………… energy of in case of a ………… system remains ………….
  1. Energy can neither be ………….. nor ………………; rather, it transforms from one form to another.
  1. Total energy in a closed system remains always ………………


B. State True or False –

  1. Energy is always created in terms of law of conservation of energy.
  1. The law of conservation of energy states that the total energy of an isolated system remains constant.
  1. Law of conservation of energy is a false idea.
  1. Newton’s laws of motion that the total momentum remains constant in a system completely separated from external factors.
  1. According to the second law, the momentum of each changes at a rate equal to the force acting on it.
Answer Key

A. Fill in the blanks

  1. Total, closed , constant
  2. Created , destroyed
  3. Constant


B. State true or false

  1. False
  2. True
  3. False
  4. True
  5. True

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