Physics Notes PDF

[Physic:] \- System: anything that is under observation \- Surrounding: anything that is not part of a system \- Kinetic energy: the energy of motion - - - - - \- Potential energy: the energy stored in an object due to its conditions of positions - - - - - - \- Formula...

[Physic:] \- System: anything that is under observation \- Surrounding: anything that is not part of a system \- Kinetic energy: the energy of motion - - - - - \- Potential energy: the energy stored in an object due to its conditions of positions - - - - - - \- Formula of: +-----------------------+-----------------------+-----------------------+ | Mechanical kinetic | Ek = mv\^2 | m: mass (kg) | | energy | | | | | | v: velocity (m/s) | +=======================+=======================+=======================+ | Gravitational | Eg = mgΔh | m: mass (kg) | | potential energy | | | | | | g: acceleration due | | | | to gravity (9.8 | | | | m/s\^2) | | | | | | | | Δh: change in height | | | | (m) | +-----------------------+-----------------------+-----------------------+ 1J = kg. m\^2/ s\^2 1kJ = 1000J \- Law of conservation of energy: law stating that the energy can neither be destroyed nor created, but is transformed from one form of energy to another, or transferred from one object to another \- Exothermic: if the reactants is higher in chemical potential energy than the products \- Endothermic: if the reactants is lower in chemical potential energy than the products \- Radiation: the mechanism of energy transfer in which atoms or molecules give off energy in the form of electromagnetic wave \- Nuclear decay: the change in an atom due to the emission of particles or radiation \- Isotopes: different form of atoms of the same elements \- Alpha decay: occurs when an ɑ particle containing 2 neutrons and 2 protons is emitted from the nucleus. (written as He, atomic mass increased by 4, atomic number decreased by 2) \- Beta decay: occurs when a neutron decay into a proton and an electron, the electron is emitted from the nucleus after that as a beta particle. (atomic mass remain, atomic number increased by 1) \- Gamma rays: occurs when a nucleus that is in an excited state emits high-energy photons of electromagnetic energy called gamma ray \- Chain reaction is a process in which one reaction leads to a series of further reactions \- Nuclear fission: a process in which a heavier nucleus is split into smaller, lighter nuclei with the release of energy \- Nuclear fusion: a process in which 2 very small nuclei combine or fuse to form a slightly larger nucleus \- Conduction: the transfer of thermal energy between two substances that are touching \- Convection: the transfer of thermal energy by the movement of heated fluids from one place to another \- Greenhouse gases: carbon, methane, dinitrogen monoxide, and water vapour \- Specific heat capacity: the amount of energy need to change the temperature of 1g of a substance by 1℃ \- Formula of the amount of energy is absorb of release by a substance: Q=mcΔT (m is g, c is J/g℃, T is ℃) The heat capacity of water is really high (4.18 J/g℃) +-----------------------------------+-----------------------------------+ | Condensation | As water vapour rises to the | | | atmosphere, it gains | | | gravitational potential energy. | | | It also releases thermal energy | | | to air molecules through | | | collision. It then cools, | | | condenses around particles in the | | | atmosphere and forms clouds. | | | | | | The change from water vapour to | | | liquid | +===================================+===================================+ | Precipitation | The water returns to the Earth's | | | surface through precipitation | | | when it rains or snows. As the | | | precipitation falls, its | | | gravitational potential energy is | | | transformed into mechanical | | | kinetic energy. This | | | transformation continues as water | | | flows from higher to lower | | | elevations on land. Thermal | | | energy is also transferred to the | | | atmosphere through friction as | | | precipitation falls. | +-----------------------------------+-----------------------------------+ | Evaporation | When water absorbs the sun's | | | energy, its molecules begin to | | | move faster as the solar energy | | | is transformed to thermal energy. | | | If enough solar energy is | | | transformed, the water evaporates | | | from the Earth\'s surface. The | | | water enters the atmosphere as | | | water vapour, bringing its | | | thermal energy with it. | +-----------------------------------+-----------------------------------+ | Transpiration | In transpiration, plants take up | | | water from the ground, or bodies | | | of water in the case of aquatic | | | plants, and release it into the | | | atmosphere as vapour. Like | | | evaporation, transpiration moves | | | thermal energy into the | | | atmosphere. | +-----------------------------------+-----------------------------------+