CHANGES IN ENERGY STORES Flashcards
what happens when energy is transferred?
the energy is then stored in one of the object’s energy stores
GEEKS LUNCH
gravitational potential energy stores electrical energy stores elastic potential energy stores kinetic energy stores sound energy transfer
light energy transfer u nuclear energy stores chemical energy stores heat (thermal) energy stores
how is energy transferred?
mechanically (by a force doing work) or electrically (work done by moving charges) by heating/radiation
what is a system?
a single object or a group of objects
what happens when a system changes?
energy is then transferred into or away from the system either between different objects in the system or between different types of energy stores
what is a closed system?
a system where neither matter nor energy can enter or leave
what is the net change in a closed system?
it’s always 0
how is energy transferred in a kettle?
water is the system and energy is transferred to the water by heating, into the water’s thermal energy store
describe the system between the water and the kettle’s heating element?
the kettle’s heating element and the water are a 2-object system
- the energy is transferred electrically to the thermal energy store of the kettle’s heating element
- which then transfers the energy by heating to the water’s thermal energy store
define work done?
when energy is transferred
when can work be done?
when a current flows or by a force of a moving an object
describe the work done when a ball is thrown upwards by a person?
energy is transferred from the chemical energy store of the person’s arm to the kinetic energy store of the ball and arm
describe the work done when a ball drops?
it accelerates due to gravity
-energy is transferred from the ball’s GPE store to its kinetic energy store
describe the work done when a car brakes?
frictional forces causes a transfer of energy from the wheel’s kinetic energy stores to the thermal energy store of the surroundings
describe the collision between a car and a stationary object?
energy is transferred from the car’s kinetic energy store to other energy stores:
- the elastic potential and thermal energy stores of the object and car body
- some energy might also be transferred away by sound waves
chemical energy stores
fuels, foods, chemicals found in batteries
energy is transferred during chemical reactions
kinetic energy stores
the energy an object has because it’s moving
gravitational potential energy stores
the energy stored in an object because of its position
elastic potential energy store
the energy stored in a springy object when you stretch or squash it
thermal energy stores
the energy a substance has because of its temperature
what happens when energy is transferred in a torch?
the torch’s battery pushes a current through the bulb
making the torch emit light and also get hot
chemical energy store in the battery - electric current in the wires-
energy transferred to the surroundings - light waves / increases in the thermal energy store of the surroundings
what happens when an object hits the floor?
all of the energy in its kinetic energy store is transferred by heating to the thermal energy store of the object and the floor
- there are sound waves moving away from the point of impact
- it’s a much smaller amount than the energy transferred by heating
GPE store - kinetic energy store -
energy transfer to the surroundings - increase in the thermal energy store of the surroundings/ sound waves
what happens when an object falls ?
it speeds up as it falls
the force of gravity acting on the object causes energy to be transferred from its GPE store to its kinetic energy store
when a ball rolls hits a wall
the system is the moving ball
-when it hits the wall some kinetic energy is transferred as sound
when a vehicle slows down
the system is the vehicle moving
-when it slows down the kinetic energy transfers to thermal due to friction between wheels and brakes
