What is "Energy" ? āĻļāĻā§āϤāĻŋ ?
Energy (āĻļāĻā§āϤāĻŋ) : Energy is the capacity to do work. āĻļāĻā§āϤāĻŋ āĻšā§āĻā§ āĻāĻžāĻŽ āĻā§°āĻžā§° āĻā§āώāĻŽāϤāĻžāĨ¤
Law of Conservation of Energy : āĻļāĻā§āϤāĻŋ āϏāĻā§°āĻā§āώāĻŖā§° āύā§āϤāĻŋ
Energy cannot be created or destroyed, but it can change from one form to another. āĻļāĻā§āϤāĻŋ āϏā§āώā§āĻāĻŋ āĻŦāĻž āϧā§āĻŦāĻāϏ āĻā§°āĻŋāĻŦ āύā§ā§ąāĻžā§°āĻŋ, āĻāĻŋāύā§āϤ⧠āĻ āĻāĻāĻž ā§°ā§āĻĒā§° āĻĒā§°āĻž āĻāύ āĻāĻāĻž ā§°ā§āĻĒāϞ⧠āĻĒā§°āĻŋāĻŦā§°ā§āϤāĻŋāϤ āĻš’āĻŦ āĻĒāĻžā§°ā§āĨ¤
Gravitational Potential Energy : āĻŽāĻšāĻžāĻāϰā§āώā§āϝāĻŧ āĻŦāĻŋāĻā§ą āĻļāĻā§āϤāĻŋ : Gravitational potential energy is the energy possessed by an object due to its height above the ground. āĻŽāĻšāĻžāĻāϰā§āώā§āϝāĻŧ āĻŦāĻŋāĻā§ą āĻļāĻā§āϤāĻŋ āĻšā§āĻā§ āĻā§āύ⧠āĻŦāϏā§āϤā§ā§° āĻŽāĻžāĻāĻŋā§° āĻāĻĒā§°āϤ āĻĨāĻāĻž āĻāĻā§āĻāϤāĻžā§° āĻŦāĻžāĻŦā§ āϞāĻžāĻ āĻā§°āĻž āĻļāĻā§āϤāĻŋāĨ¤
Formula / āϏā§āϤā§ā§° : PE = mgh
Where / āϝ’āϤ : m = mass (āĻā§°), g = acceleration due to gravity (āĻŽāĻšāĻžāĻāϰā§āώā§āϝāĻŧ āϤā§āĻŦā§°āĻŖ), h = height (āĻāĻā§āĻāϤāĻž)
Kinetic Energy : āĻāϤāĻŋāĻļāĻā§āϤāĻŋ
Kinetic energy is the energy possessed by an object due to its motion. āĻāϤāĻŋāĻļāĻā§āϤāĻŋ āĻšā§āĻā§ āĻā§āύ⧠āĻŦāϏā§āϤā§ā§° āĻāϤāĻŋā§° āĻŦāĻžāĻŦā§ āϞāĻžāĻ āĻā§°āĻž āĻļāĻā§āϤāĻŋāĨ¤
Formula / āϏā§āϤā§ā§° : KE =1/2mv2
Where / āϝ’āϤ: = mass (āĻā§°), = speed or velocity (āĻŦā§āĻ)
Relation Between Potential and Kinetic Energy (āĻŦāĻŋāĻā§ą āĻļāĻā§āϤāĻŋ āĻā§°ā§ āĻāϤāĻŋāĻļāĻā§āϤāĻŋā§° āϏāĻŽā§āĻĒā§°ā§āĻ)
Gain in kinetic energy is equal to loss in potential energy. (āĻāϤāĻŋāĻļāĻā§āϤāĻŋā§° āĻŦā§āĻĻā§āϧāĻŋ āĻŦāĻŋāĻā§ą āĻļāĻā§āϤāĻŋā§° āĻšā§ā§°āĻžāϏ⧰ āϏāĻŽāĻžāύāĨ¤)
Work (āĻāĻžāĻŽ)
Work is done when a force moves an object through a distance in the direction of the force. āĻŦāϞ⧰ āĻĻāĻŋāĻļāϤ āĻā§āύ⧠āĻŦāϏā§āϤ⧠āύāĻŋāϰā§āĻĻāĻŋāώā§āĻ āĻĻā§ā§°āϤā§āĻŦ āϞ⧠āĻāϤāĻŋ āĻā§°āĻŋāϞ⧠āĻāĻžāĻŽ āϏāĻŽā§āĻĒāύā§āύ āĻšāϝāĻŧāĨ¤
Formula / āϏā§āϤā§ā§° : W = F × d
Where / āϝ’āϤ : = Work (āĻāĻžāĻŽ), = Force (āĻŦāϞ), = Distance moved (āĻĻā§ā§°āϤā§āĻŦ)
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Energy – 2 Marks Questions with Answers : āĻļāĻā§āϤāĻŋ – ⧍ āύāĻŽā§āĻŦā§°ā§° āĻĒā§ā§°āĻļā§āύā§āϤā§āϤ⧰
1. State the law of conservation of energy. āĻļāĻā§āϤāĻŋ āϏāĻā§°āĻā§āώāĻŖā§° āύā§āϤāĻŋ āĻāϞā§āϞā§āĻ āĻā§°āĻžāĨ¤
Ans: Energy cannot be created or destroyed, but it can change from one form to another. āĻāϤā§āϤ⧰: āĻļāĻā§āϤāĻŋ āϏā§āώā§āĻāĻŋ āĻŦāĻž āϧā§āĻŦāĻāϏ āĻā§°āĻŋāĻŦ āύā§ā§ąāĻžā§°āĻŋ, āĻāĻŋāύā§āϤ⧠āĻāĻāĻž ā§°ā§āĻĒā§° āĻĒā§°āĻž āĻāύ āĻāĻāĻž ā§°ā§āĻĒāϞ⧠āĻĒā§°āĻŋāĻŦā§°ā§āϤāĻŋāϤ āĻš’āĻŦ āĻĒāĻžā§°ā§āĨ¤
2. What is kinetic energy ? Write its formula. āĻāϤāĻŋāĻļāĻā§āϤāĻŋ āĻāĻŋ ? āĻāϝāĻŧāĻžā§° āϏā§āϤā§ā§° āϞāĻŋāĻāĻžāĨ¤
Ans: Kinetic energy is the energy possessed by a body due to its motion. (āĻā§āύ⧠āĻŦāϏā§āϤā§ā§° āĻāϤāĻŋā§° āĻŦāĻžāĻŦā§ āϞāĻžāĻ āĻā§°āĻž āĻļāĻā§āϤāĻŋāĻ āĻāϤāĻŋāĻļāĻā§āϤāĻŋ āĻŦā§āϞāĻž āĻšāϝāĻŧāĨ¤)
KE = 1/2mv2
3. What is gravitational potential energy ? āĻŽāĻšāĻžāĻāϰā§āώā§āϝāĻŧ āĻŦāĻŋāĻā§ą āĻļāĻā§āϤāĻŋ āĻāĻŋ ?
Ans: Gravitational potential energy is the energy possessed by a body due to its height above the ground. āĻāϤā§āϤ⧰: āĻŽāĻžāĻāĻŋā§° āĻāĻĒā§°āϤ āĻĨāĻāĻž āĻāĻā§āĻāϤāĻžā§° āĻŦāĻžāĻŦā§ āĻā§āύ⧠āĻŦāϏā§āϤā§āϤ āϏāĻā§āĻāĻŋāϤ āĻļāĻā§āϤāĻŋāĻ āĻŽāĻšāĻžāĻāϰā§āώā§āϝāĻŧ āĻŦāĻŋāĻā§ą āĻļāĻā§āϤāĻŋ āĻŦā§āϞāĻž āĻšāϝāĻŧāĨ¤
4. Write the formula of work done. āĻāĻžāĻŽā§° āϏā§āϤā§ā§° āϞāĻŋāĻāĻžāĨ¤
Ans: W = F×d . Work done is equal to force multiplied by distance moved in the direction of force. āĻāϤā§āϤ⧰: āĻŦāϞ āĻā§°ā§ āĻŦāϞ⧰ āĻĻāĻŋāĻļāϤ āĻ āϤāĻŋāĻā§ā§°āĻŽ āĻā§°āĻž āĻĻā§ā§°āϤā§āĻŦā§° āĻā§āĻŖāĻĢāϞāĻ āĻāĻžāĻŽ āĻŦā§āϞāĻž āĻšāϝāĻŧāĨ¤
5. What happens to potential energy when kinetic energy increases ? āĻāϤāĻŋāĻļāĻā§āϤāĻŋ āĻŦā§āĻĻā§āϧāĻŋ āĻĒāĻžāϞ⧠āĻŦāĻŋāĻā§ą āĻļāĻā§āϤāĻŋā§° āĻāĻŋ āĻšāϝāĻŧ ?
Ans: When kinetic energy increases, potential energy decreases. āĻāϤā§āϤ⧰: āĻāϤāĻŋāĻļāĻā§āϤāĻŋ āĻŦā§āĻĻā§āϧāĻŋ āĻĒāĻžāϞ⧠āĻŦāĻŋāĻā§ą āĻļāĻā§āϤāĻŋ āĻšā§ā§°āĻžāϏ āĻĒāĻžāϝāĻŧāĨ¤
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