Newtons Laws

• Force (N) = mass (kg) x acceleration (m/s²)
• Newton's third law

  When two objects interact, the forces they exert on each other are equal and opposite
• The 'equal' part refers to the magnitude of the two forces
• The 'opposite' part refers to the direction of the two forces
• Normal contact force

  The force the box is exerting on you
• If the box has a much lower mass

  The box is more likely to move
• If the box is really big

  The box won't move at all, and you might be pushed backwards
• If the box is medium sized

  You might get pushed backwards a little bit, and the box might still go forwards a bit
• Newton's second law equation

  F = ma
• To accelerate an object and make it move, you need either a high force or a small mass
• The smaller object will generally move most
• Newton's first law

  A resultant force is required to change the motion of an object
• If there isn't a resultant force, the object's motion won't change
• If the resultant force on a stationary object is zero, it will remain stationary
• If the resultant force on a moving object is zero, it will carry on moving at the same velocity
• Newton's second law

  If a non-zero resultant force acts on an object, it will cause the object to accelerate
• Acceleration can result in 5 different things depending on the initial motion
• Acceleration is defined as the change in velocity divided by the change in time
• Equation F=ma

  Resultant force = mass x acceleration
• Inertia

  The tendency for the motion of an object to remain unchanged
• Inertial mass measures how difficult it is to change an object's velocity
• Large masses like the moon have a lot of inertia and require large forces to change their velocity