BTEC Applied Science Unit 5 physics

What are the standard units of mass, length and time? - Answer - Kilograms, metres and seconds What are the SI prefixes for 10^3, 10^6 and 10^9? - Answer - kilo, mega, giga What are the SI prefixes for 10^-3, 10^-6 and 10^-9? - Answer - milli, micro, nano What is work done? - Answer - The energy transferred in moving something What is power? - Answer - the rate at which work is done What happens to a gas when it is compressed? - Answer - Particles get closer together Gas pressure increases More collisions between particles and container Temperature of gas rises How do you calculate work done from a P-V graph? - Answer - The area under the graph What is efficiency? - Answer - the percentage of the work input that becomes useful work output What is thermal equilibrium? - Answer - when two objects have the same temperatures and net heat transfer is zero What is the first law of thermodynamics? - Answer - The change in a system's internal energy is equal to the difference between heat added to the system from its surroundings and work done by the system on its surroundings What are ideal gases? - Answer - All collisions are elastic All motion is random There are no forces between particles What is absolute zero? - Answer - 0 K Particles have 0 kinetic energy What is the second law of thermodynamics? - Answer - Heat will not flow from a colder body to a hotter one without an input of work. A natural process cannot fully be reversed. What is an isothermal process? - Answer - a process that occurs at constant temperature What is an adiabatic process? - Answer - no thermal energy is transferred between the system and its surroundings. What is the Carnot cycle? - Answer - an idealised engine cycle What is a heat pump? - Answer - Gas goes into the compressor. The compressor squashes the gas to make it hot. The condenser converts the gas into a liquid. The potential energy lost by the particles is released as heat. The expansion valve slows down and spreads out the liquid, like an aerosol, which cools it down The evaporator takes in energy from the surroundings to evaporate the liquid back to a gas. Define specific latent heat. -