Review the key concepts, formulae, and examples before starting your quiz.
🔑Concepts
Energy is defined as the ability or capacity to do work. Without energy, no action can be performed.
Mechanical Energy is the energy possessed by an object due to its motion or its position. It is the sum of Kinetic Energy () and Potential Energy ().
Kinetic Energy is the energy of motion. Any object that is moving, like a rolling ball or flowing water, possesses kinetic energy.
Potential Energy is stored energy due to an object's position or state. For example, water stored in a dam or a stretched rubber band.
The Law of Conservation of Energy states that energy can neither be created nor destroyed; it can only be transformed from one form to another.
Renewable energy sources are natural resources that can be replenished, such as Solar energy, Wind energy, and Hydro () energy.
Non-renewable energy sources are limited and take millions of years to form, such as Coal, Petroleum, and Natural Gas.
📐Formulae
💡Examples
Problem 1:
A boy applies a force of to push a toy car across a distance of . Calculate the work done.
Solution:
Explanation:
Work is calculated by multiplying the force applied () by the distance moved () in the direction of the force. Here, .
Problem 2:
Identify the energy transformation in an electric toaster.
Solution:
Explanation:
When we plug in a toaster, it uses electrical energy from the socket and converts it into heat energy to toast the bread.
Problem 3:
If a stone at the top of a hill has of Potential Energy and of Kinetic Energy, what is its Total Mechanical Energy?
Solution:
Total Mechanical Energy = .
Explanation:
Mechanical energy is the sum of Potential and Kinetic energy. Since the stone is at rest, its kinetic energy is zero, making the total energy equal to its potential energy.