the Physics Classroom




Much of the following has been taken directly from

the Physics Classroom

website and

the Physics Classroom

Summarized-Dynamics , although there are some differences.

Newton's First Law

 an object at rest stays at rest and an object in motion stays in motion with the same speed and in the same direction unless acted upon by an unbalanced force  objects tend to "keep on doing what they're doing", unless acted upon by an unbalanced force  

Inertia and Mass

 inertia is resistance an object has to a change in its state of motion, aka velocity more inertia an object has, the more mass it has a more massive object has a greater tendency to resist changes in its state of motion

Balanced and Unbalanced Forces

 if two individual forces are of equal magnitude and opposite direction, then forces are balanced

The Meaning of Force

 push or pull upon an object resulting from the object's


with another object  contact forces; when interacting objects are in contact o frictional, tensional, normal, air resistance, applied  action-at-a-distance forces; when interacting objects are not in contact o gravitational, electric, magnetic    unit of measure is the Newton, abbreviated by N one Newton is the amount of force required to give a 1-kg mass an acceleration of 1 m/s/s force is a vector; has a direction, common to represent with arrows using free-body diagrams

Types of Forces

 applied force is force applied to an object by a person or another object  force of gravity is force with which the Earth, or other large object attracts another object towards itself. The size of force of gravity is weight of the object. Force of gravity on earth found by the equation:

F g


. Mass refers to amount of matter that is contained by the object.   normal force is support force exerted upon object in contact with another stable object friction force is force exerted by a surface as an object moves across it or makes an effort to move across it. Usually opposes motion of an object. Two types: sliding and static friction. Magnitude of maximum amount can be calculated using:

F f

  


   air resistance is a special type of frictional force that acts upon objects as they travel through air tension force is force is transmitted through a string, rope, cable or wire spring force is the force exerted by a compressed or stretched spring Last updated June 24, 2015 1.

Drawing Free-Body Diagrams

    diagrams used to show the forces acting with arrows each arrow indicates approximate size and direction of force force arrows are labeled to indicate the exact type of force dot at center of the object and the force arrows outward from the center

Determining the Net Force

 net force is vector sum of all the forces acting

Newton’s Second Law

F net


Free Fall and Air Resistance

 only force acting is gravity  all objects will fall with the same rate of acceleration, regardless of mass

Double Trouble

 situations involving two objects are often referred to as two-body situations   system analysis: two objects are considered to be a single object moving together individual object analysis; either object is isolated and considered as separate

Newton’s Third Law

 for every action, there is an equal and opposite reaction

Resolution of Forces

 vector directed at an angle to customary coordinate axis can be resolved into components   each component being directed along one of the axes - either horizontally or vertically trigonometric functions can be used to determine components

Equilibrium and Statics

 when all forces acting on an object are balanced, then object is in equilibrium;

Fnet = 0 N

Inclined Planes

 normal force acts perpendicular to surface  perpendicular component of force of gravity is equal and opposite to normal force Last updated June 24, 2015 2.