P 1.1 Energy Flashcards
What is a system?
A system is the single object or a group of objects you’re interested in
What are the 8 energy stores?
Kinetic Gravitational potential Chemical Elastic potential Magnetic Electrostatic Nuclear Thermal
Give an example of something with chemical energy
Fuels, food, batteries
Give an example of something with kinetic energy
Anything that moves: cars, running, ball rolling, etc
Give an example of something with gravitational potential energy
Anything raised above ground level
Give an example of something with elastic potential energy
Anything stretched, e.g. springs and rubber bands
Give an example of something with magnetic potential energy
Two magnets attracting or repelling each other
Give an example of something with electrostatic energy
Two charges that attract or repel each other
Give an example of something with nuclear energy
The nucleus of an atom releases energy from this store in nuclear reactions
Give an example of something with Thermal energy
A hot water bottle. The hotter the object, the more energy in the store
How is energy transferred?
What are the four pathways?
Mechanically
Electrically
Heating
Radiation
What is the conservation of energy?
Energy can be transferred, stored or dissipated but can never be created or destroyed.
What is useful energy?
Energy that is transferred to an energy store that we did want
What is wasted energy?
Energy that is transferred to an energy store that we didn’t want.
What happens to the wasted energy of a light bulb?
Heats the air around it / surroundings
How can you reduce unwanted energy transfers?
Lubricate to reduce friction
Insulate to reduce heat loss to the surroundings
How do you calculate efficiency?
Efficiency = Useful energy / Total energy
What is thermal conductivity?
How much energy is transferred by a material.
A material with a high thermal conductivity transfer lots of energy in a short time.
A material with a low thermal conductivity are called thermal insulators.
What is work done?
The total amount of energy transferred
What is the equation the links work done, force and distance?
Work done = Force x distance
What is the equation for gravitational potential energy?
gravitational potential energy = mass x gravity x height
What is the equation for kinetic energy?
kinetic energy = 1/2 x mass x velocity^2
How is energy converted when a ball drops?
Gravitational potential energy of the high ball is converted to kinetic energy as the ball falls.
What is the formula for elastic potential energy?
Elastic potential energy = 1/2 x spring constant x extension ^2
What is the limit of proportionality e.g. for a spring?
The point at which if you carry on pulling it, it will stretch and not go back to its original shape
How does the spring constant relate to how easily a spring can be stretched?
The larger the spring constant the stiffer the spring and the more difficult it is to stretch.
