Types of Energy
What type of energy is stored in a stretched rubber band?
Elastic potential energy.
What is the primary method of energy transfer from the Sun to the Earth?
Light.
What type of energy transformation occurs in a battery-powered torch?
Chemical energy to electrical to light
If a light bulb uses 100 joules of electrical energy and produces 20 joules of light energy, what is its efficiency?
Efficiency = (20/100) * 100 = 20%.
Define kinetic energy.
Kinetic energy is the energy of motion/movement.
Which type of energy is produced by a moving car?
Kinetic energy.
How does energy transfer occur in a metal rod that is heated at one end?
Conduction.
Describe the energy transformations in a wind turbine.
Kinetic energy of wind to kinetic energy in the turbine to electrical energy.
Calculate the efficiency of a machine that uses 500 joules of energy to do 300 joules of useful work.
Efficiency = (300/500) * 100 = 60%.
What is potential energy?
Potential energy is the energy stored in an object due to its position or state.
Describe a scenario where chemical energy is converted into thermal energy.
Burning wood (chemical energy) produces heat (thermal energy).
Describe the energy transfer process in a pot of water getting heated by a gas stove.
Heat energy in flame > pot > water
Explain the energy transformations that occur in a coal-fired power plant.
Chemical energy in coal to thermal energy (heat) to kinetic energy (steam turbine) to electrical energy.
A car engine uses 2000 joules of chemical energy to produce 400 joules of kinetic energy. What is its efficiency?
Efficiency = (400/2000) * 100 = 20%.
Explain the law of conservation of energy.
The law of conservation of energy states that energy cannot be created or destroyed, only transformed from one form to another.
Explain how potential energy is converted into kinetic energy in a roller coaster.
At the top of the roller coaster, the car has maximum potential energy. As it descends, this potential energy is converted into kinetic energy.
Explain how energy is transferred in a microwave oven.
Microwaves cause water molecules in food to vibrate, transferring energy as heat.
How does a solar panel transform energy?
Solar energy to electrical
If an appliance has an efficiency of 75% and it uses 800 joules of energy, how much useful energy does it produce?
Useful energy = 75% of 800 joules = 0.75 * 800 = 600 joules.
Define heat energy and give an example.
Heat energy is the total kinetic energy of particles in a substance. Example: The heat from a hot cup of coffee.
In a hydroelectric power plant, how is gravitational potential energy transformed into electrical energy?
Water stored at height (gravitational potential energy) flows down through turbines, converting it into mechanical energy, which is then converted into electrical energy by generators.
In an ecosystem, how is energy transferred from producers (plants) to consumers (animals)?
Energy is transferred from producers (plants) to consumers (herbivores and then carnivores) through the food chain (EATING!).
Describe the energy transformations involved in a geothermal power plant.
Thermal energy from the Earth's core to mechanical energy (steam) to electrical energy.
Calculate the efficiency of a power plant that converts 10,000 joules of thermal energy into 3,000 joules of electrical energy.
Efficiency = (3000/10000) * 100 = 30%.
What is the difference between renewable and non-renewable energy sources?
Renewable energy sources can be replenished naturally (e.g., solar, wind), while non-renewable energy sources are finite and cannot be replenished on a human timescale (e.g., coal, oil).