science-physics paper 1
list the 8 energy stores
Thermal, Kinetic, Gravitational potential, Elastic potential, Chemical, Magnetic, Electrostatic, nuclear
which 4 ways can energy be transferred?
-mechnically (by doing work)
-electrically ( work done moving charges)
- by heating
- by radiation
when we talk about energy , what is a 'system'?
an object or group of objects involved in the energy transfer
what happen to energy when a system changes ?
Energy is TRANSFERRED
what is a closed system?
A system where energy cannot enter or leave
what might be a better way of describing 'wasted energy'?
Energy that is stored in less useful way
what is 'work done'?
Energy TRANSFERRED
how does throwing a ball ' do work '?
-chemical energy store in person's arm, is transferred to kinetic energy store in the person's arm and the ball
How does dropping a ball ' do work'?
Gravitational potential energy store in the ball is transferred to kinetic energy store
how do the brakes on a car 'do work'?
friction between the car's brakes and the wheels tranfers kinetic energy store into a thermal energy store
what happens if you do work against against frictional forces on an object?
temperature of the object rises
describe how is work done during a collision
car's kinetic energy store is transferred into elastic potential and thermal energy store in the car
how does boiling a kettle 'do work'?
energy is transferred to the waters thermal energy store by heating
what does the formula for elastic potential energy assume about the object (usually a spring)?
that the limit of proportionality has NOT been exceeded
give a definition for gravitational potential energy
The amount of energy gained by an object raised above ground level
whats is meant by the specific heat capacity of a substance?
The amount of energy required to raise the temperature of 1kg of the substance by 1 degrees
required practical: specific heat capacity
look at stb
Give a definition for power
-the rate at which energy is transferred
-the rate at which work is done
what is the unit for power ?
Watts [w]
whats is the watt equivalent to in terms of energy?
1 watt = 1J/s
what is conservation of energy?
energy can be:
-transferred usefully,
-stored or dissipated;
-but can never be created or destroyed
describe the energy transferred by a mobile phone ?
-energy is usefully transferred from the chemical energy of the battery
- but soem energy is dissipated (wasted) as thermal energy
list 2 ways of reducing unwanted energy transfers:
-lubrication
- thermal insulation
How does lubrication reduce wasted energy transfer ?
reduces friction
how does insulation reduce wasted energy transfer?
Prevents thermal energy loss to the surroundings
how is the thermal energy transferred through a solid materials?
conduction
How is thermal energy transferred through a liquid or a gas ?
convection
What is thermal conductivity a measure of ?
How quickly energy is transferred through a material by conduction
what affects the rate of cooling of a building
?
-thickness of walls
- thermal conductivity of walls
list 2 ways to increase efficiency of energy transfer?
-increase useful energy output
-decrease wasted energy output
why is useful energy output not equal to total enery output?
some energy is usually transferred to wasted thermal energy
what is meant by non-renewable energy resource?
will evently run out
what are the 3 types of fossil fuels
-crude oil, natural gas and coal
-fossil fuels are non-renewable
name another non-renewable energy resource ?
nuclear energy
what is meant by a renewable energy resource?
these sources can be RENEWED as they are being used and WILL NOT run out
list the 7 renewable energy resources
-the sun
-wind
-water waves
-hydro-electricity
-bio fuel
-tidal
-geothermal
state 3 major uses of different energy resources
-transport
-electricity generation
-heating