Work and Energy — Class 9 MCQs with Answers
Class 9 CBSE Science · Chapter 6
90 practice questions · 30 Easy · 30 Medium · 30 Hard · Updated
Practise the most important Class 9 CBSE Science questions from Chapter 6, "Work and Energy". You get 9 timed quizzes made from 90 NCERT-based MCQs, with answers and explanations. The questions are split into 30 Easy, 30 Medium and 30 Hard. Warm up on the basics, then move on to the exam-level questions that set top scorers in CBSE Board exams and the JEE & NEET foundation years apart.
To score well in "Work and Energy", focus on clear concepts in physics, chemistry and biology basics. Each MCQ here is timed and uses exam-style marking (+4 correct, −1 wrong, 0 skipped). This trains you to stay accurate under time pressure, as real papers need. Every question has a short explanation, so a wrong answer becomes a quick lesson. It is the fastest way to fix gaps before a test.
Use this chapter for focused revision. Start with the Easy set to check your basics on Work and Energy, then move to Medium and Hard to practise applying them. Your accuracy, streaks and XP save automatically. This chapter also adds to your overall Class 9 Science mastery score. 14 sample questions are solved in full below, with the answer and a worked explanation. Sign in free to start practising.
Key concepts: Work and Energy (Class 9 Science)
Work is done only when a force produces displacement, and energy is the capacity to do work. This chapter defines work precisely, develops kinetic and potential energy, states the law of conservation of energy, and introduces power and the commercial unit of energy.
- Work in science
- Work is done only when a force acts on an object AND the object is displaced along the direction of the force.
- Zero work
- No work is done when there is no displacement, or when the force is perpendicular to the displacement, as with a coolie carrying a load horizontally.
- Positive and negative work
- Work is positive when force and displacement point the same way and negative when they oppose, as friction does.
- Energy
- The capacity to do work, measured in the same unit as work, the joule.
Work and Energy — important questions & MCQs with answers (Class 9 Science)
14 solved questions from this chapter's difficulty levels, each with its answer and explanation. The other 76 are timed and scored when you sign in.
- Q1Easy
SI unit of work is:
A.NewtonB.PascalC.WattD.Joule✓ CorrectAnswer: D. Joule
Explanation: Work = force × displacement, so combining newtons and metres gives one SI unit: the joule (1 J = 1 N·m) — not the newton, pascal, or watt, which measure other quantities.
- Q2Easy
Kinetic energy of an object of mass m and speed v is:
A.mvB.(1/2)mv²✓ CorrectC.mghD.m/v²Answer: B. (1/2)mv²
Explanation: Kinetic energy is defined as KE = ½mv² — half the mass times speed squared, not mv or mgh, which describe momentum-like or potential energy instead.
- Q3Easy
SI unit of power is:
A.JouleB.NewtonC.Watt✓ CorrectD.HertzAnswer: C. Watt
Explanation: Power is work done per unit time, measured in watts (1 W = 1 J/s) — joules measure energy itself, not the rate at which it's used.
- Q4Easy
Work done by a constant force F displacing an object by s in the direction of force is:
A.F × s✓ CorrectB.F + sC.F / sD.F − sAnswer: A. F × s
Explanation: When force and displacement point the same way, W = F × s — the two quantities are multiplied, never added or divided.
- Q5Easy
Gravitational potential energy of a body of mass m at height h above the ground is:
A.mv²B.mgh✓ CorrectC.½ mv²D.mhAnswer: B. mgh
Explanation: Gravitational potential energy is PE = mgh (mass × gravity × height), distinct from KE = ½mv², which needs speed rather than height.
- Q6Easy
Power is defined as:
A.Work / time✓ CorrectB.Work × timeC.Force / timeD.Time / workAnswer: A. Work / time
Explanation: Power is defined as the rate of doing work, P = W/t — not work multiplied by time, a mix-up that would give the wrong units entirely.
- Q7Medium
A 10 N force moves an object 5 m in the direction of force. Work done =
A.2 JB.50 J✓ CorrectC.15 JD.500 JAnswer: B. 50 J
Explanation: W = F × d = 10 N × 5 m = 50 J — the two given values are multiplied, not added.
- Q8Medium
Potential energy of a 2 kg object at 5 m height (g = 10) is:
A.100 J✓ CorrectB.50 JC.10 JD.200 JAnswer: A. 100 J
Explanation: PE = mgh = 2 kg × 10 m/s² × 5 m = 100 J.
- Q9Medium
If 600 J of work is done in 2 minutes, power =
A.300 WB.10 WC.60 WD.5 W✓ CorrectAnswer: D. 5 W
Explanation: Power = W/t, and 2 minutes = 120 s, so P = 600 J / 120 s = 5 W — skipping the minutes-to-seconds conversion would wrongly give 300 W.
- Q10Medium
A 20 N force is applied at 60° to the horizontal to drag an object 10 m. Work done is:
A.100 J✓ CorrectB.50 JC.173 JD.200 JAnswer: A. 100 J
Explanation: W = Fd cos θ = 20 N × 10 m × cos 60° = 20 × 10 × 0.5 = 100 J — only the force component along the displacement does work.
- Q11Medium
Kinetic energy of a 2 kg ball moving at 4 m/s is:
A.8 JB.16 J✓ CorrectC.32 JD.4 JAnswer: B. 16 J
Explanation: KE = ½mv² = ½ × 2 × 4² = ½ × 2 × 16 = 16 J — square the speed first, then halve with the mass.
- Q12Hard
Work done is zero when:
A.Force is largeB.Displacement is largeC.Force is perpendicular to displacement✓ CorrectD.Force opposes motionAnswer: C. Force is perpendicular to displacement
Explanation: W = Fd cos θ is zero only when cos θ = 0, i.e. when the force is perpendicular (θ = 90°) to the displacement — not simply because force or displacement is large.
- Q13Hard
When a body falls freely, its:
A.Total mechanical energy decreasesB.Both KE and PE increaseC.KE alone increases without limitD.Total mechanical energy is conserved✓ CorrectAnswer: D. Total mechanical energy is conserved
Explanation: In free fall with no air resistance, PE steadily converts to KE, but their sum — total mechanical energy — stays constant throughout the fall.
- Q14Hard
A pump lifts 600 kg of water to height 10 m every minute (g = 10). Power is:
A.100 WB.6000 WC.1000 W✓ CorrectD.60 000 WAnswer: C. 1000 W
Explanation: Work done per minute = mgh = 600 × 10 × 10 = 60,000 J; since a minute is 60 s, power = 60,000 / 60 = 1000 W.
Start this chapter free
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Start this chapter free →Work and Energy — FAQs
What are the key concepts in Class 9 Science Work and Energy?+
Work is done only when a force produces displacement, and energy is the capacity to do work. This chapter defines work precisely, develops kinetic and potential energy, states the law of conservation of energy, and introduces power and the commercial unit of energy. Key ideas include Work in science, Zero work, Positive and negative work, Energy.
What does Class 9 Science Chapter 6 (Work and Energy) cover on XamBaaz?+
It has 90 NCERT-based MCQs on "Work and Energy": 30 Easy, 30 Medium and 30 Hard. Together they make 9 timed quizzes, and you never get the same set twice. Every question has an instant explanation. They help you prepare for CBSE Board exams and the JEE & NEET foundation years.
Are these "Work and Energy" questions free to practise?+
Yes. Sign in with Google to practise "Work and Energy" free. Full unlimited access is ₹999/year on a launch offer until 1 December 2026. No chapter is charged separately.
How should I revise "Work and Energy" for the exam?+
Start with the Easy quiz to check your basics, then try Medium and Hard to practise applying them. There are 9 timed quizzes on this chapter, so you can come back for a fresh set instead of one you have seen. Read each explanation, retry the questions you miss, and track your accuracy until it stays high.
Are these "Work and Energy" MCQs available with answers?+
Yes. 14 sample questions are shown here in full, each with the correct option and a step-by-step "Why" explanation. Sign in free with Google to start practising, with instant scoring.
Is there negative marking in the "Work and Energy" quizzes?+
Yes. The timed quizzes use exam-style marking: +4 for a right answer, −1 for a wrong one and 0 for a skip. MHT-CET and CBSE board papers have no negative marking. Our mocks for those are scored their way.
What are the important questions from Work and Energy (Class 9 Science)?+
The questions that matter most test Work in science, Zero work, Positive and negative work, Energy. This page shows 14 solved important MCQs with answers and explanations; all 90 questions on the chapter are available as timed quizzes once you sign in.
Is there an online quiz for Work and Energy?+
Yes — Class 9 Science Work and Energy has timed online quizzes at Easy, Medium and Hard levels, with instant scoring and a worked explanation on every question. The first quiz on the chapter is free.