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