DEFINITIONS: MECHANICS 3

1. Density      (MIX)
   The density of a substance is its mass per unit volume.
   The unit of density is the kilogram per cubic metre (kg m^-3).
   
   
2. Pressure     (MIX)
   Pressure is force per unit area.
   The unit of pressure is the pascal (Pa).
   One pascal is equal to one newton per square metre.
   
   
3. Archimedes' Principle     (MIX)
   When an object is partially or completely immersed in a fluid
   it experiences an upthrust equal in magnitude to the weight of the fluid displaced.
   
   
4. The Law of Flotation      (MIX)
   The law of flotation states that the weight of a floating body is equal to the weight of the fluid it displaces .
   
   
5. Boyle's Law     (MIX)
   Boyle's law states that at constant temperature
   the volume of a fixed mass of gas is inversely proportional to its pressure.
   
   
6. Newton's Law of Universal Gravitation   (MIX)
   Any two point masses in the universe attract each other with a force
   that is directly proportional to the product of their masses
   and inversely proportional to the square of the distance between them.
   
   
7. Moment of a Force     (MIX)
   The moment of a force about an axis is equal to the magnitude of the force
   multiplied by the perpendicular distance from the axis to the line of action of the force.
   The unit of moment is the newton metre (N m).
   
   
8. Conditions for Equilibrium      (MIX)
   If a body is in equilibrium then
   the vector sum of the forces in any direction is zero
   the sum of the moments about any point is zero