2.2 physics

• Mass


  A measure of the amount of matter something is made up of, a scalar measurement in kilograms (kg)
• Weight


  The force experienced by all mass because of gravity, an acceleration that causes a force of attraction between any two objects that have mass
• Objects on the Earth's surface experience a gravitational pull of ~=10N/kg
• Mass and weight


  Directly proportional and related via the gravitational field strength (g)
• Gravitational field strength (g)

  The acceleration due to gravity, varies for different planets/solar bodies
• On the moon, g = 1.6 N/kg, so a 0.2kg tea mug would weigh 0.32N on the moon instead of 2N on Earth
• Inertia


  Forces that resist any change to the velocity or state of motion of an object, depends on the mass of the object
• Newton's First Law


  • A body will travel with uniform motion along a straight line or remain at rest unless acted upon by a resultant force
• Newton's Second Law


  • A resultant force acting on a body will cause a change to its velocity, F = ma
• Newton's Third Law


  • When two objects interact, they exert equal and opposite forces on each other
• Terminal speed


  The constant speed reached by an object moving through a fluid when the drag forces equal the driving force
• For a free-falling object like a skydiver

  The terminal velocity varies depending on the mass of the diver, a greater mass means a greater weight so a greater terminal velocity
• Skydiver's journey


  1. Velocity increases non-uniformly as drag forces increase, until terminal constant velocity is reached

  2. When parachute opens, drag forces significantly increase so they slow down to a safe speed and eventually land to a stop