📘 Welcome
Hi User, you have selected Read Mode.
This is Time Free Mode for your convenience to understand every question as per your Ease and Time.
Here You get Answer and Details button. After mastering this mode, you can go for a test with Test Mode on the main page designed especially with Exam Features.
This is Time Free Mode for your convenience to understand every question as per your Ease and Time.
Here You get Answer and Details button. After mastering this mode, you can go for a test with Test Mode on the main page designed especially with Exam Features.
Q1. Energy is defined as the:
Energy is defined as the capacity or ability to do work. An object possesses energy if it can do work on another object.
Q2. The SI unit of energy is:
The SI unit of energy is the joule (J), which is the same as the unit of work. One joule is the energy required to do one joule of work.
Q3. Work done depends on:
Work done depends on the force applied, displacement, and the angle between force and displacement. The direction matters because work = F × s × cosθ.
Q4. While lifting an object, the force of gravity does:
When lifting an object, gravity acts downward while displacement is upward. Since force and displacement are opposite, gravity does negative work.
Q5. Potential energy is related to:
Potential energy is the energy stored in an object due to its position or configuration. For example, an object at a height has gravitational potential energy.
Q6. The unit of energy and work is the same because:
Energy is defined as the capacity to do work. Since work is measured in joules, energy is also measured in joules. They have the same unit.
Q7. When a retarding force acts opposite to the direction of motion, the work done is:
A retarding force acts opposite to displacement, so the work done by it is negative. This is because the angle between force and displacement is 180°.
Q8. Energy is transferred when:
Energy is transferred from one object to another when work is done, which requires force acting through displacement. When objects interact through force, energy transfer occurs.
Q9. When an object does work, it:
When an object does work on another object, it transfers some of its energy to that object. So the object doing work loses energy.
Q10. A porter lifting luggage upward does work against:
When lifting luggage upward, the porter works against the force of gravity. He applies force upward to overcome the downward gravitational force.
Q11. The object on which work is done:
When work is done on an object, energy is transferred to it. The object on which work is done gains energy.
Q12. Energy transfer occurs when:
Energy is transferred when objects interact through force and displacement occurs. This is the process of doing work.
Q13. The larger unit of energy is:
Kilojoule (kJ) is a larger unit of energy. 1 kJ = 1000 J. Newton is the unit of force and Watt is the unit of power.
Q14. Negative work is represented by:
Negative work is represented by -Fs, indicating that the force acts opposite to the direction of displacement.
Q15. A wound toy car moving on the floor shows:
A wound toy car has stored energy in its spring (potential energy). When released, this stored energy converts to kinetic energy and the car moves.
Q16. Pressing a balloon and changing its shape shows:
When a balloon is pressed, its shape changes. The energy stored due to change in shape or deformation is called elastic potential energy.
Q17. Electrical energy is used to:
Electrical energy is a versatile form of energy that can be used to do many types of work: running fans (motion), lighting bulbs (light), heating, etc.
Q18. A retarding force always acts:
A retarding force always acts opposite to the direction of motion. It slows down the moving object.
Q19. A raised object has energy because it:
A raised object has gravitational potential energy because it can do work when it falls. Energy is the capacity to do work.
Q20. Work done can be:
Work done can be positive (force and displacement in same direction), negative (force and displacement opposite), or zero (no displacement or force perpendicular).
Q21. Different forms of energy exist because:
Energy exists in various forms such as kinetic, potential, thermal, chemical, electrical, etc. This is because energy can manifest in different ways.
Q22. Mechanical energy includes:
Mechanical energy is the sum of potential energy (due to position) and kinetic energy (due to motion). These are the two forms of mechanical energy.
Q23. One joule of energy is equal to:
One joule of energy is the amount of energy required to do one joule of work. They are measured in the same unit.
Q24. A balloon exploding on pressing hard shows:
When a balloon is pressed hard, energy is transferred to the balloon. When it explodes, the stored energy is released, showing energy transfer.
Q25. Any form of energy can be identified by its ability to:
All forms of energy share the common feature that they can do work. Energy is defined as the capacity to do work.
Q26. A falling hammer driving a nail shows:
The falling hammer has kinetic energy. When it hits the nail, this energy does work by driving the nail into the surface.
Q27. An object possessing energy can:
The defining characteristic of energy is that an object possessing energy can do work on another object.
Q28. One kilojoule is equal to:
One kilojoule (kJ) is equal to 1000 joules. Kilo means thousand.
Q29. The angle between force and displacement in negative work is:
When force and displacement are in opposite directions, the angle between them is 180°. Work = F × s × cos180° = -Fs, which is negative work.
Q30. The formula used to calculate work done while lifting a mass is:
To lift a mass m through height s, the force required is mg (weight). Work done = Force × Displacement = mg × s.
Q31. Energy demand in life is:
Energy demand in life is continuously increasing due to growing population, industrialisation, and modern lifestyle.
Q32. Energy possessed by an object is measured by its:
Energy is measured by the amount of work an object can do. It is not directly measured by speed, mass, or shape.
Q33. The reason gravity does negative work while lifting an object is:
When lifting an object, displacement is upward while gravity acts downward. Since force and displacement are opposite, gravity does negative work.
Q34. A fast moving cricket ball knocking a wicket shows:
The fast moving ball has kinetic energy. When it hits the wicket, it transfers its energy to the wicket, knocking it down.
Q35. Energy from inside the earth is called:
Geothermal energy is the heat energy obtained from inside the earth. It comes from radioactive decay and residual heat from the earth’s formation.
Q36. When an object stops due to a retarding force, the work done by the force is:
A retarding force acts opposite to motion, so the work done by it is negative. It removes energy from the object, bringing it to rest.
Q37. The Sun is the biggest source of energy for:
The Sun is the primary source of energy for the entire Earth. It provides solar energy that drives weather, supports plant life (photosynthesis), and indirectly provides energy for animals.
Q38. Chemical energy is stored in:
Chemical energy is stored in the bonds of chemical compounds. It is found in fuels (like coal, petrol) and food, and is released during chemical reactions.
Q39. Energy can also be obtained from:
Nuclear energy is obtained from the nuclei of atoms through processes like nuclear fission and fusion. This is a powerful source of energy.
Q40. Heat energy is a form of:
Heat energy (thermal energy) is a form of energy. It is the energy associated with the motion of particles in an object.
Q41. Kinetic energy is related to:
Kinetic energy is the energy possessed by an object due to its motion. An object has kinetic energy when it is moving.
Q42. Work done is negative when force acts:
Work done is negative when force acts opposite to the direction of displacement. The angle between force and displacement is 180°.
Q43. Tidal energy comes from:
Tidal energy is generated from the movement of tides caused by the gravitational pull of the Moon and Sun on Earth’s oceans.
Q44. Life is impossible without:
Energy is essential for all life processes. Without energy, no work can be done, and life cannot exist.
Q45. While lifting an object upward, the force applied by you does:
When you lift an object upward, the force you apply is upward and the displacement is also upward. Since both are in the same direction, the work done by you is positive.
Q46. The work done by a porter lifting a load depends on:
Work done in lifting a load = Force × Displacement = mg × height. It depends on the weight of the load and the height lifted, not on speed or time.
Q47. Light energy helps us to:
Light energy from the Sun or other sources enables us to see objects by reflecting into our eyes. It is essential for vision.
Q48. If force and displacement are in opposite directions, work done is taken as:
When force and displacement are opposite, the angle is 180°. Work = F × s × cos180° = -Fs, so work is negative.
Q49. Many sources of energy are derived from:
Most sources of energy on Earth are derived from the Sun. Solar energy drives wind, water cycle, photosynthesis, and is the source of fossil fuels.
Q50. Work done is positive when force acts:
Work done is positive when force acts in the same direction as displacement. The angle is 0°, so W = F × s × cos0° = Fs.