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CBSE Class 11 Physics Chapter 5 Work, Energy and Power Worksheet with Answers

Work, Energy and Power forms the foundation of mechanics in CBSE Class 11 Physics. This chapter introduces scalar quantities that simplify problem-solving compared to vector force analysis. This worksheet offers structured practice across all question types found in CBSE board exams — from objective MCQs to application-based long answers. Designed for the NCERT 2025 curriculum, it reinforces the work-energy theorem, conservation principles, and real-world power calculations. Print this sheet, attempt it in 90 minutes, then verify your answers against the detailed key provided at the end.

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Key takeaways

✓Covers all core topics from NCERT Class 11 Physics Chapter 5 including work-energy theorem, conservation of energy, power and collisions with numerical applications
✓35+ questions across five sections (MCQs, fill-in-blanks, matching, short answers, long answers) plus one case-study question for comprehensive practice
✓Complete answer key with brief explanations provided for every question to enable self-study and immediate feedback
✓Moderate difficulty level designed for 90-minute timed practice, mirroring CBSE Class 11 exam pattern and marking scheme
✓Includes numerical problems on kinetic energy, potential energy, work done by variable forces and power calculations essential for board exams
✓HOTS questions and case study develop analytical thinking required for competitive exams like JEE and NEET alongside CBSE boards
✓Print-ready worksheet format allows offline practice, helping students build exam temperament and time management skills

Quick Chapter Recap: Work, Energy and Power

Before attempting the worksheet, revisit these core ideas from NCERT Class 11 Physics Chapter 5. Work is defined as the scalar product of force and displacement: W = F · s = Fs cos θ. When force and displacement are perpendicular, no work is done (cos 90° = 0). Energy is the capacity to do work, existing in kinetic (½mv²) and potential forms (mgh for gravity, ½kx² for springs). The work-energy theorem states that net work done on an object equals its change in kinetic energy: W_net = ΔKE. Conservation of energy asserts that in an isolated system, total mechanical energy (KE + PE) remains constant, though energy transforms between forms. Power is the rate of doing work: P = W/t = F·v. In collisions, momentum is always conserved; kinetic energy is conserved only in perfectly elastic collisions. These principles underpin nearly all mechanics problems in Class 11 Physics and appear regularly in CBSE board examinations worth 5-8 marks per question.

Work (scalar): W = F s cos θ; measured in joules (J); depends on force, displacement and angle between them
Kinetic Energy: KE = ½mv²; depends on mass and velocity squared; always positive
Potential Energy: Gravitational PE = mgh; Elastic PE = ½kx²; stored energy due to position or configuration
Work-Energy Theorem: W_net = KE_final − KE_initial; simplifies many dynamics problems
Conservation of Mechanical Energy: KE + PE = constant (when only conservative forces act)
Power: P = W/t = F·v; measured in watts (W); 1 HP = 746 W
Collisions: Elastic (KE conserved), Inelastic (KE not conserved); momentum always conserved in isolated systems

Section A: Multiple Choice Questions (1 mark each)

This section contains six single-correct MCQs testing conceptual understanding and formula application. Each question carries 1 mark. Choose the most appropriate option. These questions mirror the objective type that appeared in recent CBSE Class 11 Physics term exams and cover work done by conservative and non-conservative forces, energy transformations, and power calculations. Practise identifying when work is zero, when energy is conserved, and how to apply the work-energy theorem in different scenarios. Pay attention to sign conventions — work can be positive, negative or zero depending on the angle between force and displacement. CBSE typically includes 3-5 MCQs from this chapter in the annual exam.

**Q1.** A block of mass 2 kg is pushed 4 m across a frictionless floor by a horizontal force of 10 N. The work done by the force is: (A) 20 J (B) 40 J (C) 80 J (D) 8 J
**Q2.** A coolie carrying a load on his head and walking on a horizontal platform does work equal to: (A) Maximum (B) Minimum (C) Positive (D) Zero
**Q3.** The kinetic energy of a body becomes four times its initial value. The new linear momentum will be: (A) Same as initial (B) Twice the initial (C) Four times the initial (D) Eight times the initial
**Q4.** Which of the following is not a conservative force? (A) Gravitational force (B) Electrostatic force (C) Frictional force (D) Elastic spring force
**Q5.** A body of mass m is moving in a circle of radius r with constant speed v. The work done by the centripetal force in moving the body over half the circumference is: (A) mv²/r × πr (B) Zero (C) mv²r (D) πmv²
**Q6.** An engine pumps 400 kg of water through a height of 10 m in 20 s. If g = 10 m/s², the power of the engine is: (A) 2 kW (B) 4 kW (C) 20 kW (D) 40 kW

Section B: Fill in the Blanks (1 mark each)

Complete each statement with the correct term, formula or value. This section tests recall of definitions, units, and key relationships from NCERT Class 11 Physics Chapter 5. Write concise, accurate answers in the blanks provided. These questions often appear in CBSE board exams as part of the objective or very short answer section. Make sure you know SI units (joule, watt), dimensional formulas, and the conditions under which mechanical energy is conserved. Negative work implies the force opposes motion; zero work occurs when force is perpendicular to displacement. Revise the chapter summary in your NCERT textbook before attempting this section to ensure you have all definitions at your fingertips.

**Q7.** The work done by a force is zero if the angle between force and displacement is ___________.
**Q8.** The SI unit of power is ___________, which is equivalent to one joule per second.
**Q9.** According to the work-energy theorem, the net work done on a particle is equal to the change in its ___________.
**Q10.** A force is said to be ___________ if the work done by it in moving a body depends only on the initial and final positions and not on the path taken.
**Q11.** In a perfectly elastic collision, both ___________ and kinetic energy are conserved.
**Q12.** The potential energy of a spring compressed by a distance x is given by ___________.
**Q13.** One horsepower (HP) is approximately equal to ___________ watts.

Section C: True or False (1 mark each)

Read each statement carefully and write True or False. Justify your answer in one sentence wherever the statement is tricky. This section sharpens your conceptual clarity by confronting common misconceptions. For instance, many students incorrectly assume kinetic energy is always conserved in collisions, or that all forces do positive work. CBSE examiners often include such subtle statements to distinguish between rote learning and genuine understanding. Work through each statement methodically: check units, recall definitions from NCERT Class 11 Physics, and visualise the physical scenario. Even a single-word error can flip the truth value, so precision matters. Spend about one minute per statement during timed practice.

**Q14.** Work done by friction is always negative. (True/False)
**Q15.** The total mechanical energy of a system is always conserved regardless of the forces acting. (True/False)
**Q16.** Power is a scalar quantity. (True/False)
**Q17.** In an inelastic collision, kinetic energy is conserved but momentum is not. (True/False)
**Q18.** The work done by the gravitational force on a satellite moving in a circular orbit is zero. (True/False)
**Q19.** A body can have energy without possessing momentum. (True/False)

Section D: Short Answer Questions (2-3 marks each)

Answer the following in 30-50 words or show a brief calculation. Each question carries 2 or 3 marks as indicated. CBSE Class 11 Physics short-answer questions require clear definitions, derivations of two to three steps, or simple numerical problems. Use proper symbols, units, and equations. State the formula first, substitute given values, then compute the result. For theoretical questions, write in complete sentences and refer to NCERT terminology such as 'work-energy theorem' and 'conservative force'. These questions test your ability to explain concepts succinctly — a skill valuable in board exams where every mark counts. Aim for clarity over verbosity; examiners appreciate structured, point-wise answers.

**Q20.** (2 marks) Define work. Under what condition is the work done by a force on a body zero even if the body is displaced?
**Q21.** (2 marks) State the work-energy theorem. Give one practical example where this theorem simplifies problem solving.
**Q22.** (3 marks) A force F = (3i + 4j) N acts on a particle and displaces it from position r₁ = (2i + 3j) m to r₂ = (4i + 6j) m. Calculate the work done by the force.
**Q23.** (3 marks) Distinguish between conservative and non-conservative forces. Give one example of each.
**Q24.** (3 marks) A body of mass 5 kg is moving with a velocity of 10 m/s. Calculate its kinetic energy. How much work is required to stop it completely?

Section E: Long Answer and HOTS Questions (5 marks each)

These questions demand detailed explanations, multi-step derivations or comprehensive numerical solutions. Allocate 8-10 minutes per question during timed practice. CBSE awards full marks only when you show every step: draw diagrams where needed, state assumptions, write governing equations, and box final answers with units. Long-answer questions often integrate multiple concepts — for instance, combining the work-energy theorem with conservation of energy. Higher Order Thinking Skills (HOTS) questions test your ability to analyse new scenarios, such as variable forces or non-standard collision problems. Revise derivations from NCERT Class 11 Physics textbook, especially the work-energy theorem proof and the expression for elastic potential energy. Practice writing clearly; even correct mathematics loses marks if presentation is poor.

**Q25.** (5 marks) Derive the work-energy theorem for a particle moving under the influence of a variable force. Illustrate with a diagram.
**Q26.** (5 marks) A block of mass 2 kg slides down a frictionless incline of height 5 m. Using the principle of conservation of mechanical energy, find its velocity at the bottom. (Take g = 10 m/s²)
**Q27.** (5 marks – HOTS) A spring of spring constant 500 N/m is compressed by 10 cm. A block of mass 0.5 kg is placed against it and released. Calculate (a) the elastic potential energy stored, (b) the maximum velocity of the block, and (c) the height to which the block rises if the track becomes vertical after release.

Case Study Question (4 marks)

Case-study questions were introduced in the CBSE 2020 pattern and carry 4 marks. Read the passage carefully, identify the relevant physical principles, and answer the sub-questions. These often combine real-world contexts — such as hydroelectric power plants, roller coasters, or sports — with concepts from Work, Energy and Power. Each case study typically has two 1-mark MCQs and one 2-mark short answer. Underline key numerical data in the passage: masses, heights, speeds, forces. Relate them to formulas you have learned. CBSE examiners appreciate when students reference the case context in their answers, showing they understand the application rather than just the formula. Spend about 6-7 minutes on this question during the 90-minute worksheet practice.

Complete Answer Key with Explanations

Use this key to self-assess your performance. Each answer includes a brief explanation or formula reference so you understand not just what is correct, but why. Cross-check your steps in numerical problems; even if your final answer differs slightly due to rounding, the method matters more for partial marks in CBSE exams. Review any question you answered incorrectly and revisit the corresponding NCERT section. Consistent practice with immediate feedback — as provided here — accelerates mastery of Work, Energy and Power concepts. If you find certain question types challenging, consider using CBSETUTOR.ai for personalised doubt-clearing and step-by-step solutions via photo upload. The platform offers 24×7 AI tutoring at a flat ₹999/month for all subjects and classes (6-12), with a 3-day free trial to explore.

**A1.** (B) 40 J — W = Fs cos θ = 10 × 4 × cos 0° = 40 J (force and displacement both horizontal)
**A2.** (D) Zero — Force (weight + load) is vertical, displacement is horizontal; cos 90° = 0, so W = 0
**A3.** (B) Twice the initial — KE ∝ p²; if KE becomes 4×, then p becomes 2× (since p² = 2mKE)
**A4.** (C) Frictional force — Friction is non-conservative; work depends on path and energy is dissipated as heat
**A5.** (B) Zero — Centripetal force is always perpendicular to velocity, so work done W = F·s·cos 90° = 0
**A6.** (A) 2 kW — Work = mgh = 400×10×10 = 40,000 J; Power = 40,000/20 = 2,000 W = 2 kW
**A7.** 90° (or perpendicular) — When θ = 90°, cos θ = 0, hence W = 0
**A8.** watt — The SI unit of power is the watt (W)
**A9.** kinetic energy — W_net = ΔKE is the work-energy theorem statement
**A10.** conservative — Conservative forces depend only on endpoints, not path
**A11.** momentum — In elastic collisions, both momentum and KE are conserved
**A12.** ½kx² — Elastic PE = ½ × spring constant × (compression)²
**A13.** 746 — 1 HP ≈ 746 W
**A14.** False — Friction can do positive work if it acts in the direction of displacement (e.g. friction on a block at rest on an accelerating truck)
**A15.** False — Mechanical energy is conserved only when no non-conservative forces (friction, air drag) do work
**A16.** True — Power has magnitude but no direction; it is a scalar
**A17.** False — In any collision, momentum is conserved; KE is not conserved in inelastic collisions
**A18.** True — Gravity acts radially inward, orbital motion is tangential; W = F·s·cos 90° = 0
**A19.** True — A stationary body raised above ground has PE but zero momentum

How to Use This Worksheet for Maximum Benefit

Print this worksheet and attempt it under exam conditions: 90 minutes, no textbook, calculator allowed for numerical problems. Start with Section A to build confidence, then move sequentially through B, C, D, E and the case study. Mark your answers on a separate sheet so you can reuse the worksheet later. After the time limit, review the answer key section by section. Award yourself marks honestly: 1 mark per MCQ and fill-in-blank, 1 mark per true/false, 2-3 marks per short answer (partial marks if method is correct), 5 marks per long answer (award 1 mark per correct step), and 4 marks total for the case study. A score above 75% indicates solid preparation; 50-75% means you should revisit weak topics in your NCERT Class 11 Physics textbook; below 50% signals the need for guided help. CBSETUTOR.ai provides on-demand doubt solving by uploading a photo of any question you find difficult, plus chapter-wise tests and performance analytics — all for ₹999/month covering Classes 6-12, with a 3-day free trial so you can experience AI tutoring risk-free. Repeat this worksheet after one week to track improvement and build long-term retention.

Time yourself strictly for 90 minutes to simulate board exam pressure and develop pacing skills
Attempt all sections in order; do not skip the case study, which is now a regular CBSE pattern component
Write full working for numerical problems even if the answer key is brief; examiners award step marks
Review incorrect answers immediately using the explanations; note down recurring mistakes in a separate error log
Redo the entire worksheet after one week without looking at previous answers to measure retention and improvement
Pair this worksheet with NCERT exemplar problems and previous year CBSE question papers for comprehensive coverage
For persistent doubts, use CBSETUTOR.ai's AI tutor to upload question photos and receive step-by-step video or text solutions 24×7

Difficulty Level, Time Allocation and Exam Relevance

This worksheet is designed at moderate difficulty, mirroring the standard CBSE Class 11 annual exam pattern for Physics. The 35+ questions span Bloom's taxonomy levels: remember (fill-in-blanks, true/false), understand (MCQs, short definitions), apply (numerical problems), analyse (case study) and evaluate (HOTS long answers). Suggested time is 90 minutes, matching a typical 70-mark theory paper duration. Sections A-C should take about 25 minutes combined; Section D roughly 20 minutes; Section E around 25 minutes; the case study 7 minutes; leaving 13 minutes for review. Work, Energy and Power contributes approximately 8-10 marks in the CBSE Class 11 Physics board exam, appearing as 2-3 MCQs, one short numerical (3 marks) and one long derivation or problem (5 marks). Mastery of this chapter also supports mechanics topics in Class 12 and is critical for competitive exams like JEE Main and NEET, where work-energy problems form the backbone of dynamics questions. Regular worksheet practice sharpens problem-solving speed and conceptual clarity, both essential for scoring above 90% in CBSE Physics.

Moderate difficulty: mix of direct recall, formula application and multi-step reasoning suitable for average to above-average students
90-minute duration trains stamina and time management; allocate 1 min/MCQ, 3 min/short answer, 8 min/long answer
Chapter contributes 8-10 marks in CBSE Class 11 Physics annual exam; high-yield topic for board and competitive exams
Covers all NCERT learning outcomes: definitions, theorem derivations, numerical problem solving, and real-world applications
Case study and HOTS questions align with the latest CBSE pattern introduced in 2020-21, now standard in all board papers
Answer key with explanations supports self-study; no teacher required for basic doubt resolution, though guided help boosts efficiency
Repeatable resource: attempt monthly to benchmark progress and identify weak areas before final exams

Frequently asked questions

What topics from NCERT Class 11 Physics Chapter 5 are covered in this worksheet?+

This worksheet covers all core topics: definitions of work, kinetic and potential energy, the work-energy theorem, conservation of mechanical energy, power, conservative versus non-conservative forces, elastic and inelastic collisions, and numerical applications including variable forces and spring energy. It mirrors the NCERT 2025 syllabus comprehensively.

How much time should I allocate to complete this worksheet?+

Allocate 90 minutes under exam conditions. Spend roughly 25 minutes on Sections A-C (objective questions), 20 minutes on Section D (short answers), 25 minutes on Section E (long answers), 7 minutes on the case study, and reserve 13 minutes for review and rechecking your calculations and units.

Is the answer key provided with step-by-step solutions?+

Yes, the worksheet includes a complete answer key with brief explanations for every question. Numerical problems show key steps and formulas used, theoretical answers reference NCERT definitions, and common mistakes are highlighted so you understand not just the correct answer but the reasoning behind it.

What is the difficulty level of this worksheet compared to CBSE board exams?+

The difficulty is moderate, matching the standard CBSE Class 11 annual Physics exam. Most questions are at NCERT and NCERT Exemplar level, with a few HOTS and case-study items slightly above to prepare you for scoring 90+ and for competitive exams like JEE or NEET alongside boards.

Can I use this worksheet for JEE or NEET preparation as well?+

Absolutely. Work, Energy and Power is a high-weightage mechanics topic in JEE Main and NEET. This worksheet's numerical problems and HOTS questions build the problem-solving skills required for competitive exams, while also ensuring you cover the CBSE syllabus thoroughly for board marks.

How many marks does Chapter 5 carry in the CBSE Class 11 Physics board exam?+

Work, Energy and Power typically contributes 8-10 marks out of 70 in the CBSE Class 11 annual theory paper. Expect 2-3 MCQs (3-4 marks), one short numerical or definition (2-3 marks), and one long derivation or application problem (5 marks). Mastery here significantly boosts your overall score.

What should I do if I score below 50% on this worksheet?+

First, review the answer key section by section and identify which topics caused most errors. Revisit those sections in your NCERT Class 11 Physics textbook and solve the in-text examples again. Then re-attempt this worksheet after 3-4 days. For personalised help, try CBSETUTOR.ai's 3-day free trial to get instant AI tutor support on your weak areas.

Are fill-in-the-blank and true/false questions part of the CBSE exam pattern?+

Yes, CBSE often includes objective-type questions such as fill-in-the-blanks, true/false, and match-the-following in the term exams and sometimes in the annual board paper's Section A. Practising them here ensures you are comfortable with quick recall under time pressure.

How is the case study question different from other long-answer questions?+

The case study presents a real-world scenario (e.g. hydroelectric plant, roller coaster) followed by 2-3 sub-questions. It tests your ability to extract data from a passage, apply physics concepts in context, and answer both MCQs and short problems. CBSE introduced this format in 2020; it now appears regularly and carries 4 marks.

Can I reuse this worksheet for revision before the board exam?+

Yes, print multiple copies or write answers on separate sheets. Reattempt the worksheet every 2-3 weeks to track improvement and reinforce concepts. Repeated timed practice builds exam temperament, reduces silly mistakes, and ensures formulas and derivations stay fresh in memory even months after first learning them.

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