Welcome to StudyMats. This comprehensive educational guide for Class 9 Science: Work and Energy Solved Worksheet | Bilingual (Hindi & English) is prepared to assist students in preparing effectively for their school, board, and competitive examinations. All questions, exercise solutions, and concept notes strictly adhere to the latest NCERT curriculum and CBSE guidelines.
Class 9 Science: Work and Energy Solved Worksheet
Boost your exam preparation with this comprehensive Class 9 Science: Work and Energy Solved Worksheet, specifically designed for both Hindi and English medium students. This bilingual practice set covers the entire NCERT syllabus, featuring high-probability MCQs, conceptual short answers, and solved physics numericals on Kinetic and Potential energy. Whether you are a student looking for a quick chapter revision or a teacher searching for a ready-to-print assignment, this interactive worksheet—complete with a hidden answer key—provides a structured way to master complex topics like the Law of Conservation of Energy and commercial units of power. Perfect for scoring high marks in the 2026 school exams and building a strong foundation for competitive tests.
Work and Energy – Solved Worksheet
Class 9 Science | Chapter: Work and Energy | Bilingual (English & Hindi)
Section A: MCQs (1 Mark Each)
Q1. A pair of bullocks exerts a force of 140 N on a plough. If the field is 15 m long, the work done is:
बैलों की एक जोड़ी एक हल पर 140 N का बल लगाती है। यदि खेत 15 मीटर लंबा है, तो किया गया कार्य कितना है?
(a) 210 J (b) 2100 J (c) 1400 J (d) 150 J
Q2. When displacement is perpendicular to the direction of force, the work done is:
जब विस्थापन बल की दिशा के लंबवत होता है, तो किया गया कार्य होता है:
(a) Positive (b) Negative (c) Zero (d) Maximum
Q3. If velocity of an object is doubled, its kinetic energy becomes:
यदि किसी वस्तु का वेग दोगुना कर दिया जाए, तो उसकी गतिज ऊर्जा हो जाएगी:
(a) Double (b) Half (c) Four times (d) One-fourth
Q4. 1 kilowatt hour (kWh) is equal to how many Joules?
1 किलोवाट घंटा (kWh) कितने जूल के बराबर होता है?
(a) 3.6 × 105 J (b) 3.6 × 106 J (c) 36 × 105 J (d) 3.6 J
Section B: Short Answer (2 Marks)
Q5. Define 1 Joule of work and write its formula.
1 जूल कार्य को परिभाषित करें तथा उसका सूत्र लिखें।
Q6. What is the work done by gravity on a satellite moving around the earth? Justify.
पृथ्वी के चारों ओर घूमने वाले उपग्रह पर गुरुत्व बल द्वारा किया गया कार्य कितना होता है? कारण लिखिए।
Q7. State the Law of Conservation of Energy.
ऊर्जा संरक्षण का नियम बताइए।
Section C: Numerical & Long Answer (3-4 Marks)
Q8. Calculate the kinetic energy of a car of mass 1000 kg moving with a velocity of 18 km/h.
18 किमी/घंटा के वेग से चल रही 1000 किलोग्राम द्रव्यमान की कार की गतिज ऊर्जा ज्ञात करें।
Q9. An electric bulb of 60W is used for 6 hours per day. Calculate the 'units' of energy consumed in one day.
60W का एक विद्युत बल्ब प्रतिदिन 6 घंटे उपयोग किया जाता है। एक दिन में खर्च की गई ऊर्जा की 'यूनिट' ज्ञात करें।
Q10. A certain force acting on a 20 kg mass changes its velocity from 5 m/s to 2 m/s. Calculate the work done by the force.
20 kg द्रव्यमान पर लगने वाला एक बल इसके वेग को 5 m/s से 2 m/s में बदल देता है। बल द्वारा किए गए कार्य की गणना करें।
Detailed Solutions (विस्तृत समाधान)
Ans 1: (b) 2100 J
Calculation: W = F × s = 140 N × 15 m = 2100 J.
Ans 2: (c) Zero
Reason: Angle between force and displacement is 90°, and cos 90° = 0.
Ans 3: (c) Four times
Reason: KE = ½mv². Since velocity is squared, doubling it makes KE 4 times.
Ans 4: (b) 3.6 × 106 J
Calculation: 1 kWh = 1000W × 3600s = 3,600,000 J.
Ans 5: 1 Joule is the work done when a force of 1N displaces an object by 1m in force direction.
1 जूल वह कार्य है जब 1N बल किसी वस्तु को बल की दिशा में 1m विस्थापित करता है।
Formula: W = F × s
Ans 6: Zero. Because gravitational force is radial (inward) and displacement is tangential. They are at 90°.
Ans 7: Energy can neither be created nor destroyed; it can only be transformed from one form to another. Total energy remains constant.
ऊर्जा को न तो बनाया जा सकता है और न ही नष्ट किया जा सकता है; यह केवल एक रूप से दूसरे रूप में बदलती है।
Ans 8: m = 1000 kg, v = 18 km/h = 18 × (5/18) = 5 m/s.
KE = ½ × 1000 × (5)² = 500 × 25 = 12500 J.
Ans 9: Power = 60W = 0.06 kW, Time = 6 h.
Energy = Power × Time = 0.06 × 6 = 0.36 Units (kWh).
Ans 10: Work done = Change in KE = ½m(v² - u²)
W = ½ × 20 × (2² - 5²) = 10 × (4 - 25) = 10 × (-21) = -210 J. (Negative work as velocity decreases).
💡 Important Exam & Study Tips
- Master NCERT Fundamentals: Ensure thorough familiarity with standard textbook definitions, formulas, and in-text examples before solving advanced problems.
- Step-by-Step Presentation: In board examinations, neat presentation, correct formula application, and labeled steps earn maximum step-marking.
- Practice Under Timed Conditions: Regular practice with previous years' question papers (PYQs) builds exam speed and accuracy.
📚 Related Study Materials on StudyMats
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❓ Frequently Asked Questions (FAQs)
Q1: Are these solutions aligned with the latest rationalized syllabus?
Yes, all study notes and practice questions on StudyMats strictly follow the updated NCERT textbook pattern and CBSE assessment guidelines.
Q2: How can I prepare this chapter for highest marks?
Review the theory thoroughly, solve all textbook exercise questions, and repeatedly practice the high-frequency questions provided in this guide.