Class 9 Science Chapter 7: Work, Energy, and Simple Machines — practice questions with answers
Free practice for Class 9 Science, Chapter 7: Work, Energy, and Simple Machines. Try the solved questions below, then take a free test with instant marking and explanations.
59 questions20 easy, 28 medium, 11 hardNCERT · CBSE · State boards
Sample questions with solutions
Q1. In science, when is work done on an object?
- When a force displaces the object in the direction of the force
- Whenever a force is applied
- When you think hard
- When an object is at rest
Show answer
Answer: A. When a force displaces the object in the direction of the force
Why: W = F × s. [p.117–118, p.136]
Why: W = F × s. [p.117–118, p.136]
Q2. A force of 50 N lifts a bag through 2 m in the direction of the force. How much work is done (J)?
Show answer
Answer: 100 (± 0)
Why: W = 50 × 2 = 100 J. [p.118]
Why: W = 50 × 2 = 100 J. [p.118]
Q3. A 5 kg wheat bag is lifted slowly through 1 m. How much work is done against gravity (g = 10 m/s², J)?
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Answer: 50 (± 0)
Why: W = mgh = 50 J. [p.117]
Why: W = mgh = 50 J. [p.117]
Q4. Lifting 3 identical bags together to the same height needs how much work compared with lifting 1 bag?
- 3 times as much
- The same
- One-third
- 9 times as much
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Answer: A. 3 times as much
Why: Work ∝ force × distance. [p.117]
Why: Work ∝ force × distance. [p.117]
Q5. What is the kinetic energy of a 2 kg ball moving at 3 m/s (J)?
Show answer
Answer: 9 (± 0)
Why: K = ½mv² = 9 J. [p.122]
Why: K = ½mv² = 9 J. [p.122]
Q6. A 200 g ball is thrown 10 m up. What potential energy does it have at the top (g = 10 m/s², J)?
Show answer
Answer: 20 (± 0)
Why: mgh = 0.2 × 10 × 10 = 20 J. [p.126]
Why: mgh = 0.2 × 10 × 10 = 20 J. [p.126]
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Frequently asked questions
How many practice questions are there for Class 9 Science Chapter 7: Work, Energy, and Simple Machines?
59 questions (20 easy, 28 medium, 11 hard). A few are solved on this page; the free test shows the answer and explanation for every question after you submit.
Is this chapter from the NCERT book?
Yes — it follows the NCERT Class 9 Science syllabus, used by CBSE and many state boards.