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b) Work = Force × Displacement
Reasoning: Work is defined as the product of the force applied and the displacement of the body.b) It has the capacity to do one joule of work.
Reasoning: A body is said to have an energy of one joule if it has the capacity to do one joule of work.c) Magnetic energy
Reasoning: Magnetic energy is the energy possessed by a magnet which can attract and move certain metals such as iron and nickel.a) All of its potential energy is converted to kinetic energy.
Reasoning: As a weight falls, its potential energy is progressively converted to kinetic energy. Just before hitting the ground, all potential energy is converted to kinetic energy.
joule (J)1°C (or one degree Celsius)electricalkinetic
False (When work is done on a body, its energy increases. When work is done by a body, its energy decreases.)True (A very strong beam of light can move very tiny particles such as electrons.)True (Chemical energy from food undergoes changes and is stored in our muscles" as muscular energy.)False (According to the “Myth vs Fact” section, many plugged-in" appliances continue to consume energy even when they are turned off.)
Chemical Energy: The energy stored in matter. It is released only when matter undergoes a chemical change (such as burning of fuels or chemical reactions).Mechanical Energy: The energy acquired by an object by virtue of its position (potential energy) or its state of motion (kinetic energy). Total mechanical energy is the sum of kinetic energy and potential energy.
Kinetic Energy vs. Potential Energy:Kinetic Energy: The energy possessed by an object by virtue of its motion. It depends on the mass of the object and the speed of the object. (Example: A moving carrom striker).Potential Energy: The energy stored in an object by virtue of its position above the ground or a change in its shape. It depends on the mass of the object, its height above the ground, or the level of stretching/compression. (Example: Stretched rubber band).Work and Energy:Work: Done when an applied force causes displacement of a body. Mathematically,  
 .Energy: The capacity to do work. A body spends energy while doing work, and gains energy when work is done on it. Both share the same SI unit (joule).
Positions A and C. At these extreme positions, the bob is at its maximum height from the ground. Since it momentarily comes to rest at these peaks, its speed is zero, meaning its kinetic energy is zero, and all of its mechanical energy is stored as potential energy.Position B. Position B is the lowest point of the swing. As the bob falls from A to B, its potential energy is converted into kinetic energy. At B, it has the lowest height (zero potential energy) and maximum speed, meaning its kinetic energy is at its maximum.The Law of Conservation of Energy. This law states that energy can neither be created nor destroyed, but only transformed from one form to another.
A cricket ball has more mass than a tennis ball. Since kinetic energy depends on the mass of the object (greater mass leads to greater kinetic energy at the same speed), the cricket ball possesses more kinetic energy and therefore delivers a harder impact, causing more hurt.Relationship: 1 calorie is approximately equal to 4.186 joules (or 4.2 joules). 
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 Examples of potential energy due to position/height:A child sitting on the top of a slide.Water stored in a dam.A stone lifted from the ground to a height.Nuclear energy is stored in the nucleus of atoms. It is released when the nucleus of atoms either split (nuclear fission) or combine (nuclear fusion).
Two uses:Used in nuclear weapons/explosions to create powerful blast waves.Used to produce heat energy, which produces steam to turn turbine blades to generate electricity.
Energy Transformations:a) Microphone: Sound energy is converted into electrical energy.b) Photosynthesis in plants: Light energy (from the sun) is converted into chemical energy.c) Dry cells/batteries (while in use): Chemical energy is converted into electrical energy.d) Steam engines: Heat energy is converted into mechanical energy.e) Electric geysers/heaters: Electrical energy is converted into heat energy.Energy transformations of a rising and falling ball:When the ball is thrown vertically upwards, it has maximum speed and therefore maximum kinetic energy at the point of release.As it rises, it loses speed but gains height. Its kinetic energy is progressively converted into potential energy.At its maximum height, the ball momentarily stops. Here, its kinetic energy becomes zero, and its potential energy reaches its maximum value.As the ball falls back down, it loses height but gains speed. Its potential energy gets converted back into kinetic energy.Just before touching the ground, the height is zero (minimum potential energy) and speed is maximum, meaning it has maximum kinetic energy.Throughout this entire process, the sum total of kinetic energy and potential energy remains constant at every point, demonstrating the Law of Conservation of Energy.
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Answer key
Prepared by: learnloophq@gmail.com
Chapter: 03. Energy
SECTION A: Multiple Choice Questions (MCQs)
SECTION B: Fill in the Blanks
SECTION C: True or False
SECTION D: Explanation of Terms
SECTION E: Differentiate Between
SECTION F: Diagram-Based Questions
SECTION G: Short Answer Questions
SECTION H: Long Answer Questions
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