Physics P1 Flashcards
Give 4 energy stores:
Thermal
Kinetic
Gravitational Potential
Elastic Potential
Chemical
Magnetic
Electrostatic
Nuclear
Describe the energy transfers that occur as a ball falls to the ground.
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.
Then, elastic store when it hits the ground.
If energy is transferred to an object’s kinetic energy store, what happens to its speed?
Increases
What kind of energy store is energy transferred to when you compress a spring?
Elastic potential energy store
What is the definition of the specific latent heat capacity of a material?
How hard it is to heat something up.
Materials that need to gain lots of energy in their thermal energy stores to warm up also transfer loads of energy when they cool down again.
They can ‘store’ a lot of energy.
Describe an experiment to find the s.h.c. of a material
1) Measure the mass, then wrap in an insulating layer
2) Measure the initial material temperature, and set the potential difference of the power supply to 10V. Turn it on and start a stopwatch.
3) Record the temperature and current (I) every minute for 10 minutes. Current stays the same and temperature increases
4) Turn off power supply. Calculate shc
State the conservation of energy principle:
Energy can be transferred usefully, stored or dissipated, but can never be created or destroyed.
Define power
Power is the rate of energy transfer, or the rate of doing work.
What are the units of power?
It is measured in watts (1 watt = 1 joule of energy transferred per second)
How can you reduce unwanted energy transfers in a machine with moving, touching components?
Lubrication
Thermal insulation
Does a high thermal conductivity mean there is a high rate of energy transfer?
Yes
What is thermal conductivity?
A measure of how quickly het=at energy is transferred through material
Give 2 ways to prevent unwanted energy transfers in a home
1) Cavity walls -> air gap reduces energy transferred by conduction
2) Lost insulation -> reduce convection currents (cycle of heat rising and cooling and sinking)
3) Double-glazed windows -> air gap between two sheets of glass to prevent energy transfer by conduction
4) Draught excluders -> around doors and windows reduce energy transfers by convection
Do thicker walls make a house cool down quicker?
No, because thicker walls have lower thermal conductivity so there is a slower rate of energy transfer so the building will cool down more slowly.
Give 3 renewable energy sources
The sun (solar)
Wind
Water waves
Hydro-electricity
Bio-fuel
Tides
Geothemal
