science wa1

• weight = mass x gravitational force
• The conditions for work to be done are as follows:

  • There is a force acting on an object.
  • The object moves through a distance.
  • The object moves in the direction of the force.
• W.D (work done) = force x distance covered
• the transfer of energy between 2 objects may cause changes in the state of rest or motion of an object. this can:

  • move,
  • change the speed,
  • change the direction,
  • stop a moving object
• pressure in liquid: pressure = height x density x gravitational force
• cells > cellulose > molecule > atoms
• • atoms are found in elements
  • are the simplest unit of an element
  • cannot be seen with the naked eye
• an atom contains 3 sub atomic particles:

  -proton

  -neutron

  ~both form the nucleus of an atom

  -electron

  ~moves around the nucleus
• proton = positive charge

  neutron = no charge

  electron = negative charge
• number of protons = number of electrons
• number above chemical symbol is known as the proton number
• an atom combined with the same or different elements can form molecules
• friction is the force that opposes motion between two surfaces that are in contact with each other