Physics Ch 4 Flashcards
Force
a push or a pull; a vector quantity (magnitude & direction)
Dynamics
Considers the forces that affect the motion of moving objects & systems
Free Body Diagram
technique used to illustrate all the external forces acting on a body
Restoring force
force an object uses to pull itself back to its relaxed shape
Newton’s 1st Law of Motion
a body at rest remains at rest, or if in motion, remains in motion at a constant velocity unless acted on by a net external force
Inertia
the property of a body to remain at rest or to remain in motion with constant velocity
Law of Inertia
Newton’s 1st law often called this
Mass
inertia of an object measured by this
Newton’s 2nd Law of Motion
mathematically states the cause and effect relationship between force and changes in motion; acceleration is proportional to net external force
Acceleration
a change in velocity; net external force causes this
External force
acts from outside the system of interest
Friction
force that opposes the motion past each other of objects that are touching
Net External Force
vector sum of all external forces
Newton
SI unit of force
weight (w)
net force on a falling object; gravitational force on an object from the nearest large body; a vector quantity; w = mg
Free fall
when the net external force on an object is its weight
Newton’s 3rd law of motion
whenever one body exerts a force on a 2nd body, the 1st body experiences a force that is equal in magnitude and opposite in direction to the force that it exerts
thrust
reaction force
Normal force
if the force supporting a load is perpendicular to the surface of contact between the load and its support (N)
Tension
force along the length of a medium, especially a force carried by a flexible medium (ex. rope, cable)
Real forces
forces with a physical origin
Fictitious forces
those that occur because an observer is in an accelerating frame of reference
Inertial frame of reference
one in which all forces are real and equivalently, one in which Newton’s laws have the simplest forms
Carrier particles
fundamental particle of nature that is surrounded by a characteristic force field; photons are carriers of the electromagnetic force
Force field
region in which a test particle will experience a force
