CBSE Class 9 Physics Chapter 10 Work and Energy Worksheet with Answers

Work is done when a force applied on an object causes displacement in the direction of the force. The formula is W = F × d × cos(θ), where θ is the angle between force and displacement. If force is perpendicular to displacement, no work is done. Kinetic energy (KE = ½mv²) is energy due to motion, while potential energy (PE = mgh) is stored energy due to position. The Law of Conservation of Energy states that energy can neither be created nor destroyed, only transformed from one form to another. Power (P = W/t) measures the rate of doing work, with SI unit watt. The commercial unit of energy is kilowatt-hour (kWh), used in electricity bills; 1 kWh = 3.6 × 10⁶ J. In real-life situations, mechanical energy often converts to heat and sound due to friction, but total energy remains conserved. Understanding these concepts helps solve numerical problems and interpret everyday energy transformations like a falling ball, a moving vehicle, or water stored in a dam.

This worksheet is designed at a moderate difficulty level, suitable for regular Class 9 students preparing for school term exams and CBSE board assessments. It covers all major concepts from NCERT Class 9 Physics Chapter 10 including work, energy forms, conservation laws, and power calculations. The questions range from basic recall (MCQs and fill-in-the-blanks) to application-based short answers and higher-order thinking (HOTS) long-answer questions. A case-study question at the end tests your ability to apply multiple concepts in a real-world scenario. The suggested time to complete this entire worksheet is 90 minutes under exam conditions. If you are practicing at home, take your time to understand each solution in the answer key provided at the end. Use this worksheet as a self-assessment tool to identify weak areas and revisit those topics in your NCERT textbook or Class 9 Physics notes. Regular practice with such structured worksheets significantly improves conceptual clarity and scoring ability.

Each MCQ carries 1 mark. Choose the correct option. These questions test your understanding of definitions, formulae, and direct applications of Work and Energy concepts from CBSE Class 9 Physics syllabus. Pay close attention to keywords like 'always', 'never', 'maximum', and units mentioned in the options. Remember that work can be positive, negative, or zero depending on the angle between force and displacement. Kinetic energy is always non-negative, and potential energy is relative to a chosen reference point. Power is the rate of doing work, and the commercial unit kWh is used for practical energy measurements in households and industries across India. Carefully read each question twice before selecting your answer, as MCQs often contain distractors that seem correct at first glance but fail on closer examination of units or physical interpretation. These six questions form the foundation of objective assessment in Class 9 Physics Chapter 10 and are commonly seen in CBSE term exams and competitive scholarship tests.

Each blank carries 1 mark. Write the correct word or phrase to complete the statement. These questions assess your recall of key terminology and relationships from CBSE Class 9 Physics Chapter 10 Work and Energy. Focus on units, definitions, and direct relationships such as how kinetic energy depends on velocity, or how potential energy relates to height. Remember that work is measured in joules, power in watts, and commercial energy in kilowatt-hours. The law of conservation of energy is a fundamental principle that applies to all isolated systems, meaning total energy remains constant even as it transforms from one form to another. Fill-in-the-blank questions are common in CBSE term exams and require precise knowledge of scientific terms and standard SI units. Make sure your spelling is correct, especially for technical terms like 'joule', 'watt', and 'kinetic'. These five questions will help reinforce your understanding of the core vocabulary and relationships in this chapter.

Match the items in Column A with the correct items in Column B. Write the correct pairs in your answer sheet (e.g., 1-c, 2-a, etc.). This exercise tests your ability to connect concepts, formulae, units, and definitions from Class 9 Physics Chapter 10. For instance, you should be able to match 'work' with its SI unit 'joule', or 'kinetic energy' with its formula '½mv²'. Pay attention to the distinctions between similar terms: power is measured in watts, not joules; potential energy depends on height, not velocity. Matching questions are an effective way to revise relationships quickly and are frequently used in CBSE worksheets and internal assessments. These questions also help you organize your mental map of the chapter, making it easier to recall information during exams. Complete all five matches carefully, as even one incorrect pairing can cost you marks in the final assessment.

Answer the following questions in 30 to 50 words each. These short-answer questions require you to explain concepts, derive simple results, or solve straightforward numerical problems from CBSE Class 9 Physics Chapter 10. When writing answers, always start with the relevant formula, substitute given values clearly, show all calculation steps, and state the final answer with correct units. For conceptual questions, define terms first, then explain with an example or reason. Remember that CBSE marking schemes reward structured answers: definition, formula, substitution, and result. Practice writing concise yet complete answers, as short-answer questions carry significant weightage in Class 9 Physics exams. These five questions cover work done by forces, energy transformations, power calculations, and real-life applications. Use your NCERT Class 9 Physics textbook and notes to cross-check your understanding after attempting these questions independently.

Answer the following questions in detail (80 to 120 words or with complete derivation/numerical solution). These questions test higher-order thinking skills (HOTS), conceptual depth, and your ability to apply multiple concepts from Work and Energy together. Long-answer questions often ask for derivations (such as deriving the formula for kinetic energy or potential energy), multi-step numerical problems, or explanations involving real-world energy transformations like those in hydroelectric plants, pendulums, or roller coasters. Structure your answers with clear subheadings if needed: (i) Given data, (ii) Formula, (iii) Calculation, (iv) Result. For derivations, start from basic definitions and proceed step-by-step, justifying each mathematical operation. CBSE Class 9 Physics Chapter 10 long-answer questions are crucial for scoring high marks in board exams, so practice writing them neatly and completely. These three questions reflect the kind of challenging problems you will face in school assessments and annual exams.

Read the case study carefully and answer the questions that follow. Case-study questions are a recent addition to CBSE assessments and test your ability to apply Work and Energy concepts to real-world scenarios. They often describe a practical situation like a dam, a moving vehicle, a pendulum, or a roller coaster, and then ask you to analyze energy transformations, calculate values, or explain physical principles at work. Read the passage twice, underline key data like mass, height, velocity, and power, and then attempt each sub-question methodically. These questions carry 4 marks in total (usually four 1-mark sub-questions) and require both conceptual understanding and numerical ability. Case studies reflect CBSE focus on application-based learning and are increasingly common in Class 9 Physics term exams. This question brings together multiple concepts from Chapter 10 in a single integrated problem, mirroring how physics works in real life.

Section A Answers: 1(c) Zero, because displacement is zero when the bag is held without moving; 2(b) Double, since KE is proportional to v², if KE becomes 4 times, v becomes 2 times; 3(b) 25 kg, using PE = mgh, 500 = m × 10 × 2, so m = 25 kg; 4(c) Heat energy is not mechanical energy; 5(b) Watt; 6(b) 3.6 × 10⁶ J. Section B Answers: 7. zero; 8. velocity; 9. mgh; 10. destroyed; 11. work. Section C Answers: 1-b, 2-c, 3-d, 4-a, 5-e. Section D Answers: 17. Work is done when a force applied on a body causes displacement in the direction of force. SI unit is joule (J). 18. W = F × d = 10 × 5 = 50 J. 19. Energy cannot be created or destroyed, only transformed. Example: A falling ball converts PE to KE. 20. Kinetic energy is due to motion (e.g., moving car), potential energy is due to position (e.g., book on shelf). 21. Energy per day = 100 W × 5 h = 0.5 kWh; in 30 days = 0.5 × 30 = 15 kWh. Section E Answers: 22. Derive using work-energy theorem: W = F × s, F = ma, a = (v² - u²)/2s for u = 0, so W = m(v²/2s) × s = ½mv². KE is zero when v = 0. 23. PE(top) = 0.5 × 10 × 10 = 50 J, KE(top) = 0. At bottom, KE = 50 J, PE = 0. Total energy constant = 50 J. 24. Water PE converts to KE, then mechanical energy in turbines, then electrical energy. Efficiency less than 100% due to friction in turbines and heat losses. Section F Answers: 25(i) 100,000 J; (ii) 100,000 J (by conservation); (iii) ½ × 500 × v² = 100,000, v² = 400, v = 20 m/s; (iv) Speed would be less because some energy is converted to heat due to friction.

Many Class 9 students find Work and Energy challenging because it involves both conceptual understanding and numerical problem-solving. Questions like deriving kinetic energy, applying conservation laws to multi-step problems, or calculating power in real-world situations require clarity and practice. CBSETUTOR.ai offers a 24×7 AI tutor designed specifically for CBSE students from Class 6 to 12. You can upload a photo of any question from this worksheet or your textbook, and the AI tutor provides step-by-step solutions in seconds, explaining every formula and calculation clearly. Unlike expensive coaching that costs thousands per month per subject, CBSETUTOR.ai charges a flat ₹999 per month for every class and every subject, making quality help affordable for all Indian families. Whether you are stuck on a tricky HOTS question, need quick revision before exams, or want to clarify a concept from your NCERT Class 9 Physics notes, the AI tutor is always available on your phone. Start with a free 3-day trial and see how personalized, instant feedback transforms your learning experience and boosts your confidence in Physics Chapter 10 and beyond.

To excel in CBSE Class 9 Physics Chapter 10, follow these proven strategies. First, memorize all formulae (W = F × d × cos θ, KE = ½mv², PE = mgh, P = W/t, 1 kWh = 3.6 × 10⁶ J) and practice writing them correctly with units. Second, always draw a neat diagram or list given data before solving numerical problems; this prevents silly mistakes and earns you method marks even if the final answer is wrong. Third, understand the physical meaning of each term: work is not just any activity, kinetic energy depends strongly on velocity, and power is about how fast work is done. Fourth, practice derivations like the kinetic energy formula step-by-step until you can write them confidently in exams. Fifth, solve previous years' CBSE question papers and sample papers to understand the pattern and difficulty level of questions. Sixth, revise the law of conservation of energy thoroughly, as it appears in nearly every exam in various forms. Finally, use quality resources like NCERT Class 9 Physics solutions, reference books, and online platforms like CBSETUTOR.ai to clarify doubts instantly. Regular practice, conceptual clarity, and structured revision will help you score full marks in this chapter and build a strong foundation for Class 10 Physics.