Newton's Laws of Motion
Based on the following assumptions:
First Law of Motion
Unless acted on by some force an object stays at rest or in uniform motion.
Equal forces cancel each other out (e.g. a tug-of-war stalemate, an object hanging from a support by a string).
Second Law of Motion
The force on an object is proportional to the rate of change of momentum of the object.
- an object decelerates whena force acts on it in the opposite direction of its movement
- force of gravity is produced by an objects weight pushing it down
Mass and Weight
Since near earth's surface, the weight of a mass on earth is .
Since weight is a force, its unit is newtons.
Gravitational Field Strength
The force of gravity per unit mass on an object at that position.
Third Law of Motion
When two bodies interact, they exert equal and opposite forces on each other.
A physical quantity with direction and size.
Vectors in diagrams are depicted as arrows pointing in directions.
A physical quantity without direction.
Center of Gravity / Center of Mass
A concept that keeps objects in stable equilibrium when they stand straight upright.
For free standing objects, the lower the center of gravity the more stable the object stands.