Vector Dynamics – Terms to Know

 

  1. Dynamics - the study of the causes of motion or the relation between motion and forces.

     

  2. Force - a push or a pull. An action capable of accelerating a body (measured in Newtons). (V)

     

  3. Newton - a unit of force and is defined as the net force required to accelerate a one kilogram mass at one metre per second squared.

     

  4. Contact Force – a force exerted by one surface on another when two objects are in contact (e.g. a person’s hand pushing on a table). (V)

     

  5. Normal Force – a force exerted by one surface, perpendicular to that surface, on another surface. (A force that results from contact between two bodies – often a reaction force due to a body’s weight – e.g. the force exerted by an inclined plane, perpendicular to the plane, on an object resting on the plane.) (V)

     

  6. Friction – a force that opposes motion. (E.g. force that opposes motion when one object moves over another). (V)

     

  7. Mass – Quantity of matter in a body. A measure of the inertia of a body. (Measured in kilograms.) (S)

     

  8. Inertia – the tendency of a body to maintain its state of rest or uniform motion in a straight line.

     

  9. Weight – the force of gravity acting on a body. (Measured in Newtons; defining formula: W = mg.) (V)

     

  10. Gravitational Field Strength or Intensity - The weight per unit mass of a body. (measured in N/kg. The value near the surface of the earth is 9.8 N/kg.) (V)

     

  11. Free Body Diagram – a diagram that shows ALL forces acting on a body.

     

  12. Coefficient Of Friction – the ratio of the force of friction acting on an object to the normal force acting on that object (symbol used is usually µ). (defining equation: FFRICTION = µ FNORMAL.) If an object is stationary the coefficient of friction is called the coefficient of static friction. If the friction is in motion the coefficient of kinetic friction.

     

  13. Tension – the condition of a body subjected to equal but opposite forces which tend to stretch it. Tension forces are the "pulls" exerted by stretching strings, rods, etc. on the bodies to which they are attached. They act along the direction of the string or rod and are measured in newtons. (V)

     

  14. Newton’s First Law of Motion – The Law of Inertia – every body continues in its state of rest or of uniform speed in a straight line unless it is compelled to change that state by forces acting on it.

     

  15. Newton’s Second Law of Motion – the acceleration of a body is directly proportional to the net force acting on it and is inversely proportional to its mass. The direction of the acceleration is in the direction of the applied net force. (defining equation is Fnet = ma.)

     

  16. Newton’s Third Law of Motion – whenever one object exerts a force on a second object, the second exerts an equal and opposite force on the first.