Chapter 11: Work and Energy
Solved textbook questions with step-by-step explanations.
Grade 6 Q&A: Chapter 11: Work and Energy
Welcome to the Questions and Answers section for Grade 6 Environmental Studies (Part One), Chapter 11: "Work and Energy." This chapter introduces us to the fundamental concepts of work and energy, which are crucial for understanding how everything around us moves and functions. We will explore what constitutes 'work' in a scientific sense, delve into various forms of energy such as mechanical, heat, light, sound, and electrical energy, and learn about their practical applications in our daily lives.
Important Questions and Answers
Q1: What is work in science?
Answer: In science, work is done when a force causes an object to move a certain distance in the direction of the force.
Q2: What is energy?
Answer: Energy is the ability to do work.
Q3: Name different forms of energy.
Answer: Different forms of energy include mechanical energy, heat energy, light energy, sound energy, electrical energy, chemical energy, and nuclear energy.
Q4: What is mechanical energy? Name its two types.
Answer: Mechanical energy is the energy possessed by an object due to its motion or position. Its two types are kinetic energy and potential energy.
Q5: What is kinetic energy? Give an example.
Answer: Kinetic energy is the energy possessed by an object due to its motion. Example: A moving car, a flying bird, flowing water.
Q6: What is potential energy? Give an example.
Answer: Potential energy is the energy stored in an object due to its position or state. Example: Water stored in a dam, a stretched rubber band, a stone held at a height.
Q7: What is heat energy? Give an example of its use.
Answer: Heat energy is the energy associated with the random motion of atoms and molecules. It is used for cooking food, heating water, and running engines.
Q8: What is light energy? Give an example of its source.
Answer: Light energy is a form of electromagnetic radiation that allows us to see. The sun is the primary natural source of light energy.
Q9: What is sound energy? Give an example.
Answer: Sound energy is produced by vibrations and travels in waves, allowing us to hear. Example: Music from a speaker, a ringing bell, human speech.
Q10: What is electrical energy? Give an example of its use.
Answer: Electrical energy is produced by the flow of electric charges (electrons). It is widely used to power appliances, lights, and machinery in homes and industries.
Q11: What is the law of conservation of energy?
Answer: The law of conservation of energy states that energy can neither be created nor destroyed; it can only be transformed from one form to another.
Q12: Give an example of energy transformation.
Answer: When a light bulb glows, electrical energy is transformed into light energy and heat energy. When a fan rotates, electrical energy is transformed into mechanical energy.
Q13: What are renewable sources of energy? Give examples.
Answer: Renewable sources of energy are those that can be replenished naturally over a relatively short period. Examples: Solar energy, wind energy, hydro energy, geothermal energy, biomass energy.
Q14: What are non-renewable sources of energy? Give examples.
Answer: Non-renewable sources of energy are those that exist in limited quantities and take millions of years to form, so they cannot be replenished quickly once used up. Examples: Coal, petroleum, natural gas, nuclear energy (from uranium).
Q15: Why is it important to use renewable energy sources?
Answer: It is important to use renewable energy sources because they are sustainable, produce less pollution, and help conserve non-renewable fossil fuels for future generations.
Q16: How is solar energy used?
Answer: Solar energy is used to generate electricity using solar panels, heat water in solar water heaters, and cook food in solar cookers.
Q17: How is wind energy generated?
Answer: Wind energy is generated by using wind turbines, which convert the kinetic energy of wind into electrical energy.
Q18: What is hydro energy?
Answer: Hydro energy (or hydroelectric energy) is the energy generated from the force of falling or flowing water, typically by building dams across rivers.
Q19: What is the importance of energy in our daily lives?
Answer: Energy is essential for almost all our daily activities, from walking and talking to cooking, lighting our homes, running vehicles, and operating electronic devices.
Q20: What is the difference between potential and kinetic energy?
Answer: Potential energy is stored energy due to position or state, while kinetic energy is the energy of motion. An object can have one or both forms of mechanical energy.
Q21: Give an example where potential energy is converted into kinetic energy.
Answer: When a ball is dropped from a height, its potential energy (due to height) is converted into kinetic energy (as it falls and gains speed).
Q22: How is chemical energy stored in food?
Answer: Chemical energy is stored in the chemical bonds of the molecules that make up food. When we digest food, these bonds are broken, releasing energy for our body's functions.
Q23: What is the main source of energy on Earth?
Answer: The sun is the main source of energy on Earth, directly or indirectly providing almost all forms of energy we use.
Q24: How does a battery provide electrical energy?
Answer: A battery stores chemical energy, which is converted into electrical energy through chemical reactions when the battery is connected to a circuit.
Q25: What is the unit of work and energy?
Answer: The standard international (SI) unit of both work and energy is the Joule (J).
Q26: Why should we conserve energy?
Answer: We should conserve energy to reduce our dependence on non-renewable sources, minimize environmental pollution, lower energy costs, and ensure energy availability for future generations.
Q27: How can we save energy in our daily lives?
Answer: We can save energy by switching off lights and fans when not needed, using energy-efficient appliances, walking or cycling for short distances, and using public transport.
Exercise Solutions
Q1: Fill in the blanks.
- The ability to do work is called energy.
- Energy possessed by an object due to its motion is kinetic energy.
- Energy stored in an object due to its position is potential energy.
- The sun is the main source of light energy.
- Energy can neither be created nor destroyed; it can only be transformed.
Q2: Match the pairs.
(Note: As an AI, I cannot create interactive matching. I will provide the correct pairs.)
- Moving car - Kinetic energy
- Water in a dam - Potential energy
- Solar panel - Light energy
- Electric fan - Electrical energy
- Burning wood - Heat energy
Q3: True or False.
- Work is done when a force causes movement. True
- Heat energy is not a form of energy. False
- Fossil fuels are renewable sources of energy. False
- Energy can be created from nothing. False
- Wind energy is a clean source of energy. True
Q4: Answer the following questions.
- What is work? Explain with an example.
Answer: Work is done when a force applied to an object causes it to move a certain distance in the direction of the force. Example: Pushing a trolley across a room. - What is energy? Name its different forms.
Answer: Energy is the ability to do work. Its different forms include mechanical, heat, light, sound, electrical, chemical, and nuclear energy. - What is the difference between kinetic and potential energy?
Answer: Kinetic energy is the energy of motion (e.g., a running person), while potential energy is stored energy due to position or state (e.g., a ball held at a height). - What are renewable and non-renewable sources of energy? Give examples.
Answer: Renewable sources can be replenished naturally (e.g., solar, wind). Non-renewable sources are limited and take millions of years to form (e.g., coal, petroleum).
Q5: Give reasons.
- Energy cannot be created or destroyed.
Reason: Energy cannot be created or destroyed according to the law of conservation of energy. It only changes from one form to another, meaning the total amount of energy in a closed system remains constant. - We should use solar energy.
Reason: We should use solar energy because it is a renewable source, meaning it will not run out; it is clean and produces no pollution, helping to protect the environment and reduce reliance on fossil fuels. - Water stored in a dam has potential energy.
Reason: Water stored in a dam has potential energy because it is at a certain height above the ground. This stored energy can be converted into kinetic energy when the water is released, which can then be used to generate electricity.
References
- Maharashtra State Board Environmental Studies (Part One) Standard Six Textbook (2015 Edition) - Chapter 11: Work and Energy.
- Maharashtra State Board 6th Standard Environmental Studies Syllabus.
- Balbharati Environmental Studies Part 1 Textbook.