Chapter 10: Work and Energy — Online MCQ Test
SCIENCE · CLASS 9th · Karnataka State Board
Practice Chapter 10: Work and Energy with a free chapter-wise online MCQ test.
This chapter covers: This chapter details scientific concept of work kinetic energy potential energy law of conservation of energy and rate of doing work power..
AI-generated questions from basic to board-exam level, with instant results and explanations.
Chapter 10: Work and Energy — Important Questions & Answers
What is the SI unit of work?
- A. Joule
- B. Watt
- C. Newton
- D. Kilogram
Answer: A. Joule
Work is measured in joule (J) in the SI system. One joule is the work done when a force of 1 newton moves an object by 1 metre in the direction of the force.
Work is measured in joule (J) in the SI system. One joule is the work done when a force of 1 newton moves an object by 1 metre in the direction of the force.
Which of the following is the correct formula for work done?
- A. Work = Force × Distance
- B. Work = Mass × Acceleration
- C. Work = Power × Time
- D. Work = Energy ÷ Time
Answer: A. Work = Force × Distance
Work done by a constant force is the product of force and displacement in the direction of the force. This is the basic formula used in Class 9.
Work done by a constant force is the product of force and displacement in the direction of the force. This is the basic formula used in Class 9.
A force of 10 N moves an object by 3 m in the direction of the force. How much work is done?
- A. 13 J
- B. 30 J
- C. 7 J
- D. 300 J
Answer: B. 30 J
Work done = Force × displacement = 10 × 3 = 30 J. Since force and displacement are in the same direction, work is positive.
Work done = Force × displacement = 10 × 3 = 30 J. Since force and displacement are in the same direction, work is positive.
Which of the following is true according to the law of conservation of energy?
- A. Energy can be created but not destroyed
- B. Energy can be destroyed but not created
- C. Energy can neither be created nor destroyed, only transformed from one form to another
- D. Energy remains always in the same form
Answer: C. Energy can neither be created nor destroyed, only transformed from one form to another
The total energy of an isolated system remains constant. Energy only changes form, such as from potential energy to kinetic energy.
The total energy of an isolated system remains constant. Energy only changes form, such as from potential energy to kinetic energy.
A machine does 1200 J of work in 4 s. What is its power?
- A. 300 W
- B. 4800 W
- C. 400 W
- D. 30 W
Answer: A. 300 W
Power = Work / Time = 1200 / 4 = 300 W. This is a direct application of the definition of power.
Power = Work / Time = 1200 / 4 = 300 W. This is a direct application of the definition of power.