Forces Flashcards
What is a force?
A force is a PUSH or a PULL on something.
what are the 4 fundamental forces?
gravitational, electromagnetic, weak nuclear and strong nuclear
gravitational force
Force of attraction between all objects
e.g. planets in orbit
electromagnetic force
Force cased by electric charges
e.g. chemical reactions; electricity
weak nuclear force
Forces in-between elementary particles
e.g. involved in particle transformations
strong nuclear force
Attraction between neutrons and protons
e.g. nuclear reactions
A force is a ____ or ____ upon an object
resulting from the object’s _________ with
another object.
push; pull; interaction
Whenever there is an ________ (two objects
affecting each other in some way) between
two objects, there is a _____ upon each of the
objects.
interaction; force
When the _____ ceases, the two
objects no longer experience the force. Forces
_____ exist as a result of an interaction.
interaction; only
all forces (interactions) between objects can be placed into two broad categories:
contact forces and forces resulting from action at a distance
____________ are types of forces in which the
two interacting objects are _____________ each other.
For example: Friction, air resistance, applied forces (when a push a book across the desk).
Contact forces; physically
contacting
_______________ are types of forces
in which the two interacting objects are not in
physical contact with each other, yet are able
to exert a __________ despite a physical
separation.
Action-at-a-distance forces; push or pull
Examples of action-at-a-distance forces
gravitational forces (e.g., the sun and planets exert a gravitational pull on each other despite their large spatial separation)
electric forces
magnetic forces
Force is a quantity which is measured using
the standard metric unit known as the ________.
One Newton is the amount of force required to
give a 1-kg mass an acceleration of 1 m/s2. A
Newton is abbreviated by a “N.”
Newton
A force is a ________
vector quantity
Recall, that a vector quantity is a quantity which has both magnitude and direction.
To fully describe the force acting upon an object, you must describe…
both the magnitude (size) and the direction.
it is common to represent forces using diagrams
in which a force is represented by ________
an arrow
system diagrams
System Diagrams (sketch showing all the objects
involved)
free body diagram or FBD
shows only the forces.
Free-body diagrams are diagrams used to show the ___________________ of all forces acting upon an object in a given situation.
relative magnitude and direction
The size of the arrow in a free-body diagram is
reflective of the ________ of the force.
magnitude
The direction of the arrow reveals the ________
direction which the force is acting.
dynamics
the study of the causes of motion
applied force
a force that results when one object makes contact with another and pushes or pulls on it
tension
a pulling force from a rope
or string on an object that always points
toward the rope or string
normal force
a perpendicular force
exerted by a surface on an object in
contact with the surface; the normal force
always points away from the surface
friction
opposes the sliding of two
surfaces across one another; friction
acts opposite to the motion or attempted
motion
force of gravity
force of attraction
between any two objects
net force, (also known as total force or
resultant force)
the sum of all the forces acting on an object.
inertia
the property of an object that resists change in its state of rest or motion
Newton’s first law of motion
if the net force acting on an object is zero, the object will remain at rest or move at a constant velocity
implications
there must be an _____________ in order to change motion
external force
moving objects will continue to move in a ___________ at a __________ unless acted on by an __________________________
straight line; constant speed; external net force greater than zero
factors
inertia is directly proportional to the ______ of the object
mass
factors
therefore, _____ objects are harder to _____ moving and will also be harder to ____ moving
heavier; start; stop
true or false:
the gravitational field intensity and force of gravity are the same thing
false
true or false
the force of friction operates in the same direction as the motion
false
inertia is a property of objects that resist changes to the object’s state of motion or rest
true
true or false
gravitational force exists only on Earth
false
true or false
the normal force always acts in the exact opposite direction as the force of gravity
false (not always)
true or false
The net force on an object is the sum of all the forces acting on it.
true
true or false
If the net force on an object is constant and the mass decreases, then the acceleration increases.
true
true or false
Newton’s third law states that for every action force, there is a simultaneous reaction force of equal magnitude acting in the same direction.
false
