definitions6

• What is pressure?

  -Applied force acting per unit (contact) area

  Pressure = applied force / contact area

  -SI unit: Pascal (Pa) , Newton per metre square ( N/m^2 )

  -Scalar quantity -> independent of direction, dependent on only magnitude
• What is Pascal's principle / Pascal's law?

  If a pressure is applied to an enclosed liquid, the pressure is transmitted to all other parts of the liquid undiminished.
• What is density?

  -Mass per unit volume

  -Scalar quantity

  -SI Unit: kilogram per cubic metre (kg/m^3)

  (common unit is gram per cubic centimetre (g/cm^3)
• What is the formula of water pressure

  *All units when calculating water pressure should be in SI unit

  Pressure = height (m) * density (kg/m^3) * gravitational field strength (N/kg)
• Why is mercury barometer reliable?

  vertical height of mercury column depends only on atmospheric pressure

  -> not size of tube / how deep tube is placed
• Why is water not used in a barometer?

  -water easily evaporates due to low boiling point

  -longer tube required due to lower density of water (around 10m)

  -difficult to read the height of water because it is colourless
• Why is mercury used in a barometer?

  mercury is the highest density liquid at room temperature
• What is energy required for and its SI unit?

  Energy is required to do work

  SI Unit: Joule (J)
• What are the 4 ways of energy transfer?

  -Mechanically (by a force acting over a distance)

  -Heating (due to a temperature difference)

  -Propagation of waves (Electromagnetic waves) / (Mechanical sound waves) / (infrared waves) / (light waves)

  -Electrically (by electric current)
• What is the formula to calculate the amount of energy in the kinetic store of a body moving at speed v?

  Ek = (1/2) mass(kg) * speed^2 (m/s)
• What is the formula to calculate the amount of energy in the gravitational potential store of a body near Earth's surface at height h above ground

  Ep (J) = mass (kg) * gravitational field strength (N/kg) * height (m)
• What is the principle of conversion of energy?

  energy cannot be created / destroyed

  energy can be transferred from one store to another

  Total energy of an isolated system is constant
• What is work done?

  constant force on an object

  product of force and distance moved by object in the direction of the force

  SI unit: Joule (J)