Review the key concepts, formulae, and examples before starting your quiz.
🔑Concepts
Energy is defined as the capacity or ability to do work. Without energy, no task can be performed.
Solar Energy: This is the energy we get from the Sun. It is the primary source of energy on Earth. It provides both heat energy and light energy. We use solar panels to convert this into electricity.
Wind Energy: Moving air is called wind. Wind possesses energy that can be used to rotate the blades of a windmill or a wind turbine to generate electricity.
Water Energy: Moving or falling water has energy. This energy is used in dams to turn large turbines to produce hydroelectricity. Historically, waterwheels were used to grind grain.
Work and Force: Work is said to be done only when a force applied to an object causes it to move through a certain distance. The relationship is expressed as .
Renewable Sources: Solar, wind, and water are considered renewable sources of energy because they are naturally replenished and do not run out.
📐Formulae
💡Examples
Problem 1:
A student pushes a toy car with a force of and it moves a distance of . Calculate the work done.
Solution:
Explanation:
Work is calculated by multiplying the force applied by the distance the object moves in the direction of the force.
Problem 2:
Which source of energy is used by a solar cooker to cook food, and what form of energy is involved?
Solution:
The source is the Sun (Solar Energy). It uses energy.
Explanation:
The solar cooker traps the from sunlight to increase the temperature inside the vessel to cook food.
Problem 3:
Identify the energy transformation when wind turns a wind turbine.
Solution:
Explanation:
The moving air (wind) has kinetic energy which turns the blades (mechanical work), which is then converted into electricity by a generator.