Physics Final Study Guide: Chapter 4

Gravitational
The attractive force that exists between all objects with mass

Newton’s First Law
“An object that is at rest will remain at rest, and an object that is moving will continue to move in a straight line with constant speed, if and only if the net force acting on the object is zero.”

Force
An action exerted on an object that causes a change in motion

Field force
A force that is exerted without contact

Interaction pair
Two forces that are in opposite directions and have equal magnitudes

Tension
A force exerted by any segment of a rope or string on an adjoining segment

Net force
The vector sum of two or more forces action on an object

Equilibrium
When the net force on an object is zero

Drag force
A force exerted by a fluid on an object moving through the fluid

Newton’s second law
“The acceleration of a body is directly proportional to the net force on it and inversely proportional to its mass.”

Apparent weight
The force exerted on a scale by an object and other forces action upon the object

Contact force
A force that acts on an object by touching it

Newton’s third law
“The two forces in an interactive pair act on different objects and are equal in magnitude and opposite in direction.”

Normal force
A perpendicular contact force exerted by a surface on another object

System
A defined object or group of objects

Inertia
The tendency of an object to resist changes in its motion

Agent
The specific, identifiable cause of a force

Free-body diagram
In this diagram, a dot represents an object and arrows represent each force acting on it, with their tails on the dot and their points indicating the direction of the force

Terminal velocity
The constant velocity that a falling object reaches when the drag force equals the force of gravity

Weightlessness
When an object’s apparent weight is zero, the object is in this state

External world
Everything surrounding a system that exerts force on that system

Weight
name of gravitational force acting on object

9.8 m/s2
magnitude of acceleration caused by gravity

g
symbol for the acceleration caused by gravity

Fg
symbol for the due to gravity force

mg
expression for the weight of an object

newton
unit of force

mass
property of an object that does not vary from location to location

weightlessness
having an apparent weight of zero