Newton's First Law:
(Law of Intertia) a body in a state of motion or at rest will remain in that state unless acted upon by a net Force.
Newton's Second Law:
- when a net force is applied to a body of mass m, the body will be accelerated in the same direction as the force applied to the mass.
- This is expressed by the formula F = ma
- (SI unit: Newton (N) = kg*m/s2
Newton's Third Law:
- If body A exerts a force on body B, then B will exert a force back onto A that is equal in magnitude, but opposite in direction.
- This is expressed as, Fb = -Fa.
Newton's Law of Gravity
All forms of matter experience an attractive force to other forms of matter in the universe.
- The magnitude of the force is represented by:
: a scalar quantity that measures a body's inertia.
- Weight (W): a vector quantity that measures a body' gravitational attraction to the earth.
- W = mg
occurs when forces are applied against an object in such a way as to cause the object to rotate around a fixed pivot point, aka the fulcrum.
Where, F is the magnitude of the force, r is the distance between the fulcrum and the point of force application, and θ is the angle between F and the lever arm.
Free Falling Objects
For a free falling object, the net external force is just the weight of the object:
F = W
Substituting into the second law equation gives:
a = W / m = (m * g) / m = g
The acceleration of the object equals the gravitational acceleration. The mass, size, and shape of the object are not a factor in describing the motion of the object. So all objects, regardless of size or shape or weight, free fall with the same acceleration.