physics chapter 6 Flashcards
what is energy
energy is a physical quantity that can be measured
what is the unit that is used for energy
the joule (J) is a commonly used unit of energy
what are the different types of energy transfers
- by heating
- by forces
- by electric currents
- by electromagnetic waves
- by sound waves
what are the different stores of energy
- kinetic
- elastic
- gravitational potential
- electrostatic
- chemical
- internal
- nuclear
how do we calculate the amount of energy that the body has
kinetic energy ( in joules ) = 1/2 ( mass of the body x speed of the body ^2)
Ek = 1/2 ( mv^2)
what are some examples of the use of principle of conservation of energy
- an ideal pendulum swinging
- a robot waiter on the move
- hammering nail
how useful is fossil fuel store and how is it produced
- examples of fossil fuels are petroleum, natural gas, coal and wood
- when a fuel is burnt in air, for cooking food ina pot, heating transfers energy from the chemical store of the fuel to the thermal stores of the pot, the food and the surroundings
how do we calculate the size of the gravitational potential store of a body at a height above ground
gravitational potential energy = mass of the body x gravitational field strength x height
Ep = mgh
what is the principle of conservation of energy
the principle of conservation of energy states that energy cannot be created or destroyed. it can only be transferred from one energy to another. the total amount of energy in the different energy stores before and after a process must be the same
what is a common unit used to measure the unit of work
joules ( j )
how can we calculate the work done by a constant force
work done by a constant force = constant force x distance moved by the object in the direction of the force
w = fd
define work done
work done by a constant force on an object is the force and distance moved by the object in the direction of a force
what are the disadvantages of biofuels
Environmental pollution from the gases produced during burning contributes to global warming
what are the different examples of major energy resources
- fossil fuels
- biofuels
- hydropower
- geothermal resources
- solar power
- nuclear power
what are the advantages of fossil fuels
- widely available at a large scale
- relatively cheaper in cost of production
what are the disadvantages of fossil fuels
environmental pollution from the gases, produced during burning, contributes to global warming
what are the advantages of biofuels
- Widely available at a large scale
- Relatively cheaper in cost of production
how useful is biofuel store and how is it produced
- Examples of biofuels are ethanol, biodiesel and biogas, which are derived from biomass. Biomass comes from living materials such as corn, sugar cane, vegetable oils, animal fats and animal manure.
- Biofuels have chemical stores of energy.
- Heating transfers energy from the chemical store of biofuels to the thermal store of food or water during cooking or boiling.
how useful is hydropower store and how is it produced
- Water movement provides a kinetic store of energy to generate electrical power. This hydropower or water power can be obtained from ocean waves, tides and water behind hydroelectric dams.
- Water behind hydroelectric dams has gravitational potential store of energy. This energy in the gravitational potential store is transferred mechanically to the kinetic store by releasing the water and letting it flow downwards. The flowing water will cause the turbines to spin.
- As the turbines spin, the kinetic store of energy of the turbines is transferred by electric current to factories and homes.
what are the advantages of hydropower
- Clean method of producing cheap electricity
- Renewable energy resource as the water movement can be continually regenerated
what are the disadvantages of hydropower
- High cost of building dams, turbines and generators
- Damming a river for hydroelectric power station may cause damage to the environment surrounding the river
how useful is geothermal resource store and how is it produced
- In certain areas, such as volcanic regions, geological forces push large amounts of hot molten rocks near the Earth’s surface. These places are known as geothermal hotspots.
- Water that makes its way to these geothermal hotspots is heated and subjected to great pressure.
- This heated water has a large thermal store of energy. It is forced to the surface as boiling water and steam to drive turbines to generate electrical power
what are the advantages of geothermal resources
- Clean source of naturally available thermal energy
- Renewable energy resource
what are the disadvantages of geothermal resources
- Environmental pollution caused by the release of poisonous gases such as hydrogen sulphide into the atmosphere
- Not widely available as they are found only in certain areas around the world
