Learn: Energy Store and Transfers, Energy Equations, Efficiency, Gravitational Potential Energy, and Kinetic Energy

Welcome!Today we'll explore energy stores and transfers, energy equations, efficiency, gravitational potential energy, and kinetic energy. Let's build a strong foundation for your understanding of these key concepts!

What are Energy Stores?Energy can exist in different stores, such as chemical, kinetic, gravitational potential, and thermal energy. These represent the ways energy is held within objects or systems.For example, food contains chemical energy, a moving car has kinetic energy, and a raised object has gravitational potential energy. Understanding these stores helps us track how energy is transferred and used.

Energy TransfersEnergy can be transferred from one store to another through processes such as mechanical work, electrical work, heating, or radiation. These processes allow energy to move between stores.For example, when you push a car, the chemical energy in your muscles is transferred to the car as kinetic energy through mechanical work.

Energy Transferred EquationThe amount of energy transferred can be calculated using the equation: Energy transferred = Power × Time. This shows how much energy is moved based on the rate of transfer (power) and the time it occurs.For example, a 60W light bulb running for 2 hours transfers 120 Wh of energy (60 × 2).

What is Efficiency?Efficiency tells us how much of the energy we put into a device is usefully transferred compared to the wasted energy. It is calculated using the formula:Efficiency = (Useful energy transferred ÷ Total energy supplied) × 100.Efficiency is expressed as a percentage. A high efficiency means less energy is wasted, making the device more effective.

Gravitational Potential EnergyGravitational potential energy is the energy stored in an object due to its height above the ground. It depends on the object's mass, height, and the gravitational field strength.The equation to calculate gravitational potential energy is:Ep = m × g × h, where:- Ep = Gravitational potential energy (Joules, J)- m = Mass (kg)- g = Gravitational field strength (N/kg, usually 9.8N/kg on Earth)- h = Height (m)

Kinetic EnergyKinetic energy is the energy an object has because it is moving. It depends on the object's mass and speed.The equation for kinetic energy is:Ek = 1/2 × m × v², where:- Ek = Kinetic energy (Joules, J)- m = Mass (kg)- v = Speed (m/s)

Review Time!Great work! You've learned about energy stores, transfers, equations, efficiency, gravitational potential energy, and kinetic energy. Let's test your understanding!