Work and Energy Class 9 MCQs with Answers (NCERT-Based)
Work and Energy Class 9 MCQs with Answers (NCERT-Based)
CBSE Board Examination – Systematic MCQ Practice
Class: 9
Subject: Science
Section: Physics
Topic: Work and Energy
These Multiple Choice Questions (MCQs) are designed strictly as per the NCERT syllabus, making them ideal for CBSE Class 9 Science examinations. Each question includes a detailed explanation to help in concept clarity and exam preparation.
1. Work is said to be done when:
Answer: C
Work is done only when a force applied on an object produces displacement in the direction of the force. If there is no displacement, no work is done even if force is applied.
Work is done only when a force applied on an object produces displacement in the direction of the force. If there is no displacement, no work is done even if force is applied.
2. SI unit of work is:
Answer: B
Work = Force × Displacement. Unit becomes Newton × metre = Joule (J). Hence Joule is the SI unit of work.
Work = Force × Displacement. Unit becomes Newton × metre = Joule (J). Hence Joule is the SI unit of work.
3. When is work done negative?
Answer: B
Work is negative when force acts opposite to displacement, like friction opposing motion.
Work is negative when force acts opposite to displacement, like friction opposing motion.
4. Work done is zero when angle between force and displacement is:
Answer: C
Work = F × s × cosθ. At 90°, cos90° = 0, hence work done is zero (e.g., centripetal force in circular motion).
Work = F × s × cosθ. At 90°, cos90° = 0, hence work done is zero (e.g., centripetal force in circular motion).
5. Energy is defined as:
Answer: A
Energy is the ability or capacity of a body to do work. Without energy, work cannot be performed.
Energy is the ability or capacity of a body to do work. Without energy, work cannot be performed.
6. Kinetic energy depends on:
Answer: C
K.E. = ½mv². It depends on both mass and square of velocity. Increase in speed greatly increases kinetic energy.
K.E. = ½mv². It depends on both mass and square of velocity. Increase in speed greatly increases kinetic energy.
7. SI unit of energy is:
Answer: A
Energy and work share the same SI unit because energy is the capacity to do work.
Energy and work share the same SI unit because energy is the capacity to do work.
8. Potential energy of an object at height h is:
Answer: A
Gravitational potential energy = mgh. It depends on mass, gravity and height above ground.
Gravitational potential energy = mgh. It depends on mass, gravity and height above ground.
9. Moving bus possesses:
Answer: B
Because it is in motion. Any moving object has kinetic energy.
Because it is in motion. Any moving object has kinetic energy.
10. Energy stored in a stretched spring is:
Answer: B
Stretching stores elastic potential energy which converts to kinetic energy when released.
Stretching stores elastic potential energy which converts to kinetic energy when released.
11. Law of conservation of energy states:
Answer: C
Energy only transforms from one form to another; total energy remains constant.
Energy only transforms from one form to another; total energy remains constant.
12. A raised hammer has:
Answer: B
Because of its position above ground, it stores gravitational potential energy.
Because of its position above ground, it stores gravitational potential energy.
13. Commercial unit of energy is:
Answer: C
Electric energy consumption is measured in kilowatt-hour (kWh), called one ‘unit’ of electricity.
Electric energy consumption is measured in kilowatt-hour (kWh), called one ‘unit’ of electricity.
14. Power is defined as:
Answer: B
Power measures how fast work is done. SI unit is Watt.
Power measures how fast work is done. SI unit is Watt.
15. SI unit of power:
Answer: B
1 Watt = 1 Joule/second. It shows rate of doing work.
1 Watt = 1 Joule/second. It shows rate of doing work.
16. 1 kWh equals:
Answer: A
1 kWh = 1000 W × 3600 s = 3.6 × 10⁶ Joules.
1 kWh = 1000 W × 3600 s = 3.6 × 10⁶ Joules.
17. Faster object has:
Answer: B
Since KE ∝ v², increase in speed greatly increases kinetic energy.
Since KE ∝ v², increase in speed greatly increases kinetic energy.
18. Work done lifting object upward is:
Answer: B
Force and displacement are in same direction; hence work is positive.
Force and displacement are in same direction; hence work is positive.
19. When object falls, PE converts to:
Answer: C
As height decreases, potential energy converts into kinetic energy.
As height decreases, potential energy converts into kinetic energy.
20. A body at rest possesses:
Answer: B
Though kinetic energy is zero, it may possess potential energy due to position or configuration.
Though kinetic energy is zero, it may possess potential energy due to position or configuration.