Topic 1 - Energy (1) Flashcards
11 12 (Energy stores and systems + Kinetic and potential energy stores) (34 cards)
What happens to the energy transferred to an object?
the energy is stored in one of the object’s energy stores
Name 8 energy stores?
1) Thermal energy stores
2) Kinetic energy stores
3) Gravitational potential energy stores
4) Elastic potential energy stores
5) Chemical energy stores
6) Magnetic energy stores
7) Electrostatic energy stores
8) Nuclear energy stores
What can thermal energy stores also be referred to as?
internal energy stores
What are the 4 ways in which energy can be transferred?
mechanically
electrically
by heating
by radiation
How is energy transferred mechanically?
by a force doing work
How is energy transferred electrically?
work done by moving charges
How is energy transferred by radiation?
e.g. by heat or by sound
What happens when a system changes?
Energy is transferred
In what two ways can energy be transferred when a system changes?
1) It can be transferred into or away from the system
2) between different objects in the system or between different types of energy stores
What is a system?
a single object or group of objects that you’re interested in
What is a closed system?
systems where neither matter nor energy can enter or leave
- the net change in the total energy of a closed system is always 0
Energy can be transferred by heating:
Thinking of water as the system, expain how energy is transferred between stores when boiling a kettle?
- energy is transferred to the water (from the kettle’s heating element) by heating, into the water’s thermal energy store (causing the temperature of the water to rise)
Energy can be transferred by heating:
Think of the kettle’s heating element and the water as a two object system, how is energy transferred between stores when boiling a kettle?
Energy is transferred electrically to the thermal energy store of the kettle’s heating element, which transfers energy by heating to the thermal energy store of the water
Energy can be transferred by doing work:
What is work done another way of saying?
energy transferred
Energy can be transferred by doing work:
In what 2 circumstances can work be done?
- when current flows (work is done against resistance in a circuit)
- by a force moving an object
Energy can be transferred by doing work:
Explain how energy is transferred between stores when a person throws a ball?
- the initial force exerted by a person to throw a ball upwards does work
- It causes an energy transfer from the chemical energy store of the person’s arm to the kinetic energy store of the ball and arm
Energy can be transferred by doing work:
Explain how energy is transferred between stores when a ball is dropped from a height?
- a ball dropped from a height is accelerated by gravity - the gravitational force does work
- it causes energy to be transferred from the ball’s gravitational potential energy store to its kinetic energy store
Energy can be transferred by doing work:
Explain how energy is transferred between stores when a car brakes?
- the friction between a car’s brakes and its wheels does work at it slows down (frictional forces cause a transfer of energy)
- It causes an energy transfer from the wheels’ kinetic energy stores tot the thermal enery stores of the surroundings
Energy can be transferred by doing work:
Explain how energy is transferred between stores when a car collides with a stationary object?
- the normal contact force between the car and the object does work
- It causes energy to be transferred from the car’s kinetic energy store to other energy stores
for example, the elastic potential and thermal energy stores of the object and the car body, some energy might also be transferred away by sound waves
What is kinetic energy?
Anything that’s moving has energy in its kinetic energy store
How is energy transferred to or away from an object’s kinetic energy store?
- energy is transferred to the store when an object speeds up
- is is transferred away from the store when an object slows down
What two factors control the energy in an object’s kinetic energy store?
- the object’s mass and speed
- the greater its mass and the faster it’s going, the more energy there will be in the object’s kinetic energy store
Which energy store will all raised objects store energy in?
gravitational potential energy sores
Explain how objects raised higher have more energy in their gravitational potential energy store?
- lifting an object in a gravitational field requires work
- this causes a transfer of energy to the gravitatinal potential energy store of the raised object
