Foundations of physics AS

• the base unit of length is the metre (m)
• the base unit of mass is the kilogram (kg)
• the base unit of time is the second (s)
• the base unit of electric current is the Ampere (A)
• the base unit of temperature is Kelvin (K)
• the base unit for the amount of substance is the mole (mol)
• Peta - (P) - 10^15
• Tera - T - 10^12
• Giga - G - 10^9
• Mega - M - 10^6
• Kilo - K - 10^3
• deci - d - 10^-1
• centi - c - 10^-2
• milli - m - 10^-3
• micro - M - 10^-6
• nano - n - 10^-9
• pico - p - 10^-12
• femto - f - 10^-15
• average speed = distance / time taken
• density = mass / volume
• a scalar quantity is a quantity that has magnitude but no direction
• a vector quantity is a quantity that has both magnitude and direction
• examples of scalar quantities include:

  • mass
  • energy
  • distance
  • speed
• examples of vector quantities include:

  • momentum
  • velocity
  • weight
  • displacement
  • acceleration
  • force
• scalar quantities can be added or subtracted from each other.
• the length of the line representing a vector represents the magnitude of the vector
• the direction in which the arrowhead points represents the direction of the vector.
• when two vectors are parallel you call one direction positive and the other negative and then add the vectors together to find the resultant
• perpendicular forces act at right angles to each other
• how to draw a vector triangle:

  • draw a line to represent the first vector.
  • draw a line to represent the second vector, starting from the end of the first vector (tip to tail)
  • to find the resultant vector, join the start to the finish.
• To find the magnitude of a vector in a vector triangle, you use pythagoras
• To find the direction of the vector in a vector triangle you use triganometry
• To resolve a force F into the x and y directions, the two components of the force are:

  • Fx = Fcosx
  • Fy = Fsinx

  where x is the angle made with the x direction. These equations can be used with any vector in the place of x.