physics energy

topic one : energy

what are the factors that increase kinetic energy?

speed and mass

what is kinetic energy?

the energy possessed due to motion

what is the equation for kinetic energy?

equation for weight

weight = mass × gravitational field strength

what is gravitational potential energy?

the energy of an object at height

what is the equation for gravitational potential energy?

gravitational potential energy = mass × gravitational field strength × height

what is elastic potential energy?

the energy stored in an object when it is compressed or stretched.

what is the equation for elastic potential energy?

epe=1/2 x spring constant x extension²

what is specific heat capacity?

the energy needed to raise the temprature of 1kg of a substance by 1 degree celcius.

what is the unit for specific heat capacity?

J/ Kg °c : “joule per kilogram degree celcius”

formula for change in energy

change in energy=m c Δθ

how do you find the final temprature using this equation? (formula for change in energy)

rearrange the formula to get :change in temprature= change in energy/ mass x specific heat capacity.

what is conservation of energy?

in a closed system, energy cant be created or destroyed, only transferred.

what is work done?

the measure of energy transferred when a force moves an object through a distance.

what is the formula for work done?

work done= force(N) x distance (metres)

what is the unit for work done?

Joules or Nm

what is the difference between a closed and an open system?

what are the three ways that heat energy is transferred?

how does conduction work?

how does convection work?

how does radiation work?

what is thermal conductivity?

what is an insulator

• materials with low thermal conductivity

• energy transfer per second is very low

• e.g. air, fiberglass, wool, polystyrene

what does the energy transfer per second depend on?

• temp. difference across material

• thickness of material- e.g. wall thickness

• thermal conductivity of material

what are some ways that homes can be insulated to reduce unwanted energy transfers?

• loft insulation: made from fiberglass, the more layers of insulation the thicker and so therefore the lower rate of energy transfer

• cavity wall insulation: walls are made of a cavity between two walls with insulation in between.

• double glazing: two glass panes trap air in between, air is a good insulator and the thicker the glass the lower thermal conductivity.

what are the two equations/ definitions for power?

what is the equation for efficiency?

what is efficiency?

examples of non-renewable energy sources

examples of renewable energy recources

what is the equation for weight?

weight= mass x gravitational fs (9.8)

how does wind power work?

blades on a wind turbine are blown, spinning a generator which generates electricity.

what are the advantages and disadvantages of wind and solar power?

how does solar power work?

some of the energy absorbed by solar panels is converted into electricity.

how does geothermal energy work?

• energy stored deep beneath the earth, water is pumped onto hot rocks which creates steam which turns a generator, generating energy.

• it can also be used directly for heat by heating water and pumping it into homes.

pros and cons of geothermal energy

what is biomass energy?

fuel taken from recently living organsisms

how does hydroelectric energy work?

• rain water is collected in a resovoir to create a difference in water level in a river.

• the stored water on the higher side has a huge gravitational potential energy, and so when the water is released back into the river, it turns the blades of underwater turbines, which spins generators and generates electricity.

how does tidal energy work?

• tidal barrages trap water from a high tide and when it is released it spins the blades of turbines which spins generators which generate electricity.

• sometimes, electricity is generated by the flow passing through the undersea turbines.

pros and cons of biomass energy:

pros and cons of tidal and hydroelectric energy:

how does wave energy work?

• a wave-powered floating generator moves up and down due to waves.

• the motion turns the generator so it generates electricity.

• a cable between the generator and shore line delivers electricity to the system grid.

pros and cons of wave energy

how could you improve the thermal insulation practical?

record the measurements more frequently