Subjective Questions – Chapter: Energy
1. Define energy. How are work and energy closely related?
Energy is defined as the capacity to do work.
Work and energy are closely related because energy is required to perform any kind of work. For example, when you run, the energy stored in your body enables you to move. If there is no energy, you cannot do work. Hence, energy is essential for performing work, and doing work involves the use of energy.
Work and energy are closely related because energy is required to perform any kind of work. For example, when you run, the energy stored in your body enables you to move. If there is no energy, you cannot do work. Hence, energy is essential for performing work, and doing work involves the use of energy.
2. Distinguish between kinetic energy and potential energy.
| Kinetic Energy | Potential Energy |
|---|---|
| Energy due to motion. | Energy due to position or configuration. |
| K E=1/2 mv². | P.E= mgh. |
| Increases with speed | Increases with height or stretch. |
3. List some practices for conserving energy and preventing its wastage.
- Switch off lights and fans when not in use.
- Use energy-efficient appliances (like LED bulbs).
- Use public transport or walk.
- Use renewable sources like solar or wind energy.
- Avoid overcharging mobile phones and unplug chargers.
- Use energy-efficient appliances (like LED bulbs).
- Use public transport or walk.
- Use renewable sources like solar or wind energy.
- Avoid overcharging mobile phones and unplug chargers.
4. Energy is conserved during the production of hydroelectricity. Explain.
In hydroelectric power plants, water stored in dams has gravitational potential energy. When the water flows down, this energy is converted into kinetic energy, which turns turbines to generate electricity. The total energy remains conserved by changing its form—no energy is lost.
5. Solar devices utilise solar energy to convert it into a useful form. Comment.
Solar devices like solar cookers and solar panels use the Sun’s energy and convert it into heat or electricity. These devices are eco-friendly and help reduce dependence on fossil fuels. They make use of renewable solar energy and convert it into usable forms for daily applications.
