Definitions

• Mass


  The amount of matter present in a body
• Weight

  A gravitational force on an object that has mass
• Force


  A push or a pull
• Center of mass


  The place at which all of the object's mass is concentrated
• Resultant force


  The total amount of force acting on the object or body along with the direction of the body
• Centripetal force


  A net force that acts on an object to keep it moving along a circular path
• Compression

  Regions where particles are closer together and greater pressure
• Rarefaction


  Regions where particles are further apart and lower pressure
• Potential difference


  Work done per unit charge
• Nuclear fission


  Large unstable nucleus splits into smaller nuclei and there is a large release of energy
• Redshift


  Wavelength of light from distant galaxies increase

  Occurs when galaxies are moving away from earth
• Quantity that the redshift of a galaxy is used to calculate

  Speed of galaxy moving away from earth
• Monochromatic


  Light of a single frequency
• Simple iron-cored transformer

  Alternating current in the primary coil

  Current in primary generates changing magnetic field

  iron core transfers magnetic field to the secondary coil

  secondary coil has a changing magnetic field and cuts the iron core's magnetic field -> induced e.m.f in secondary coil
• Half life


  Time taken for number radioactive nuclei to halve
• Why are isotopes with short half-lives hazardous?

  Large number of particles produced in short time

  High decay rate

  High dose of radiation
• Absolute zero

  Temperature at which particles have least kinetic energy

  Lowest possible temperature
• Magnetic field


  Region in which a magnetic pole experience a force
• Direction of magnetic field


  Direction of the force on the N pole
• Why do countries with significant distance from Equator experience significant temperature variation throughout the year

  Rays from Sun strike the country at different angles and different number of hours per day
• Specific heat capacity


  The energy required to raise 1kg of mass
• Why are visible lights and IR used for optical fibre?

  Glass is transparent to visible light, and some IR

  They can carry high rates of data
• Beta decay


  Neutron becomes a proton and electron
• Principles of conservation of energy

  Energy cannot be created or destroyed
• unit kWh


  Energy transferred in one hour at a rate of transfer of 1kW
• Converging lens

  Reduces focal length of eye

  Rays focus on retina -> help with longsightedness
• Hubble constant

  ratio of speed (of a galaxy) to distance away (from observer)
• Nuclear fusion

  Nuclei combine

  Small nuclei to larger nuclei

  Loss of mass