General Physics
- 1.95: Energy & Resources.
Only changed from form to form, Such as from kinetic energy to thermal energy or from chemical energy to electrical energy. these changes occur due to events such a burning fuel or moving an object to a higher location or the flow of a current from a battery.
An even such as the moving of a car involves the energy change from chemical energy in fuel to thermal energy once ignited , this then converts to kinetic energy as the car thrust forward and back to thermal due to frictional forces. All of the chemical energy initially in the fuel has changed into thermal energy and kinetic energy , No energy is destroyed in the process.
Not all energy is useful to us ,such as the thermal energy lost as friction or the chemical energy present in fossil fuels , we change the type of energy in order for it to be useful , For example , in water falls the fast moving water has alot of potential energy , this is then used to drive a turbine which in turn drives a motor to produce electrical energy which is useful to us as we use electrical energy to drive our electronics and household appliances
forms of energy transfer we use are: solar energy, wind energy , nuclear energy , geothermal energy and tidal energy.
Some forms of energy transfer are more efficient than others, for example solar energy is very inefficient as most of the energy radiated from the sun is not transferred , while nuclear fission produces large amounts of energy from small samples of radioactive material such as uranium or plutonium. Although efficiency may be a problem , some energy sources are non renewable , meaning that they cannot be harvested forever , wind and solar energy are continuous and do not run out and can be considered to be renewable whilst fossil fuels such as coal and natural gas and oil are finite and can run out.
Efficiency can be calculated as useful energy output/ total energy input *100
- 1.97: Work & Power
The work done in any scenario is the energy transferred , this can be written mathematically as W=F.S which is Work equals Force.Distance which is equal to energy change . So the work done is equal to the force moved in the direction of the force causing the motion.
Power is the term we use to describe the rate of doing work , How quickly a motor can burn through fuel can be described through its power, And is equal to Work/Time.
Power is the term we use to describe the rate of doing work , How quickly a motor can burn through fuel can be described through its power, And is equal to Work/Time.
- 1.99: Pressure
A device known as a barometer is used to measure atmospheric pressure, the device contains mercury , at sea level the barometer read 760 millimeters of mercury , at higher altitudes the pressure decreases due to there being less air above you creating that pressure.
A device used to measure pressures in general is a manometer , which works in the same way as a barometer but using a tube to input a liquid or gas into the apparatus instead of using the atmosphere.
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