general

• vector - magnitude and an associated direction
• the centre of mass is the single point where an objects weight is said to act
• scalar - magnitude only
• Hooke's law = force is directly proportional to the extension
• stopping distance = thinking distance + braking distance
• human reaction time is usually 0.2 to 0.9 seconds
• thinking distance can be affected by alcohol, drugs and fatigue
• the braking distance can be affected by weather, adverse roads and vehicle conditions
• gradient = speed
• acceleration = gradient of a velocity time graph
• Newton's third law = every action has an equal and opposite reaction
• newton's first law = an object is at rest or at a constant velocity unless acted on by a resultant force
• speed = scalar
• velocity = vector
• distance = scalar
• displacement - vector
• newtons second law : f = ma
• newtons third law : Every action has an equal and opposite reaction
• If an object does return to its original shape after the forces have been removed, it is known as elastic deformation.
• if an object does not return to its original shape after the forces have been removed, it is known as inelastic deformation
• A flat line on the velocity / time graph tells us the object is moving at constant velocity.
• Newton's 3rd law : when two objects interact, the two forces they exert on each other are equal and opposite
• Air resistance is a contact force. This is because it is due to the physical contact (collisions) between an object and the particles in the air. 
• The tendency of an object to continue in its current state (at rest or in uniform velocity)is called inertia . All objects have inertia. Whether they are moving or not.