Physics Quicksheets - Newton's Laws

  1. 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.
  2. 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
  3. 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.
  4. 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:
    • Image Upload 1

    Mass (m): 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
  5. Rotational Motion
    Rotational motion 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.

    Image Upload 2

    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.
  6. 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.
Card Set
Physics Quicksheets - Newton's Laws
Kaplan Quicksheets Chapter 2