Energy Stores and Transfers Flashcards
What is a system?
An object or group of objects
What happens when something changes in a system?
Energy is transferred between its stores or to the surroundings
What is a closed system?
- No energy can escape to or enter from the surroundings
- The total energy in a closed system never changes
What is kinetic energy?
Energy an object has because it is moving
What is gravitational potential energy?
Energy an object has because of its height above ground
What is elastic potential energy?
Energy an elastic object has when it is stretched or compressed
What is thermal (or internal) energy?
Energy an object has because of its temperature (the total kinetic and potential energy of the particles in the object)
What is chemical energy?
Energy that can be transferred by chemical reactions involving foods, fuels, and the chemicals in batteries
What is nuclear energy?
Energy stored in the nucleus of an atom
What is magnetic energy?
Energy a magnetic object has when it is near a magnet or in a magnetic field
What is electrostatic energy?
Energy a charged object has when near another charged object
How can energy be transferred by heating?
Energy is transferred from one object to another object with a lower temperature
How can energy be transferred by waves?
Waves (e.g., light and sound waves) can transfer energy by radiation
How can energy be transferred by electricity?
When an electric current flows it can transfer energy
How can energy be transferred by forces (mechanical work)?
Energy is transferred when a force moves or changes the shape of an object
What happens to the energy stores when a rubber band is stretched?
Energy from your chemical store is transferred mechanically to the rubber band’s elastic potential store
What happens to the energy stores when a block is dropped from a height?
Energy is mechanically transferred (by the force of gravity) from the block’s gravitational potential store to its kinetic store
When the block hits the ground, energy from its kinetic energy store is transferred by sound waves to the thermal energy store of the surroundings
What happens to the energy stores when a kettle is boiled?
The electric current in the kettle transfers energy to the heating element’s thermal energy store. Energy is then transferred by heating from the heating element’s thermal energy store to the thermal energy store of the water.
What happens to the energy stores when an object slows down due to friction?
Energy is mechanically transferred from the object’s kinetic store to its thermal store, the thermal store of the object it is rubbing against, and to the surroundings.
What does an object’s gravitational potential energy store depend on?
- Height above ground
- Gravitational field strength
- Mass
What does an object’s kinetic energy store depend on?
- Mass
- Speed
What is power?
How much work is done (or how much energy is transferred) per second.
What does work done mean?
Energy transferred
What is the unit of power?
watts (W)
What is lubrication?
A way of reducing unwanted energy transfer due to friction
What is streamlining?
A way of reducing energy wasted du to air resistance or drag in water
What is thermal insulation?
A way of reducing energy wasted due to air resistance or drag in water
What can happen to energy?
- Transferred usefully
- Stored
- Dissipated (wasted)
What is efficiency?
A measure of how much energy is transferred usefully
What is one joule of work?
The work done when a force of 1N causes an object to move 1m in the direction of the force
