# Shared Flashcard Set

## Details

Chapter 4
Forces & Newton's Laws of Motion
46
Physics
01/16/2015

Term
 force
Definition
 a push or a pull
Term
 contact forces
Definition
 forces that arise from physical contact between two objects (ex. throwing a basketball or pulling a water skier)
Term
 noncontact forces/action-at-a-distance forces
Definition
 forces that objects exert on one another even though they are not touching
Term
 Is mass a scalar or vector quantity?
Definition
 scalar
Term
 Newton's first law of motion
Definition
 an object continues in a state of rest or in a state of motion at a constant velocity unless compelled to change that state by a net force
Term
 net force
Definition
 the vector sum of all forces acting simultaneously on a body
Term
 What is the purpose served when a net force acts on an object?
Definition
 to change the object's velocity, not to sustain it
Term
 inertia
Definition
 the natural tendency of an object to remain at rest or in motion at a constant velocity
Term
 mass
Definition
 a quantitative measure of inertia
Term
 SI unit of inertia & mass
Definition
 kilogram (kg)
Term
 How are mass and inertia correlated?
Definition
 the larger the mass, the greater the inertia
Term
 Can "mass" and "weight" be used interchangeably?
Definition
 no!
Term
 Are accelerating reference frames inertial or noninertial?
Definition
 noninertial
Term
 inertial reference frames
Definition
 one in which Newton's first law of inertia is valid
Term
 Newton's second law of motion
Definition
 when a net external force "sigma vector F" acts on an object of mass "m", the acceleration "vector a" that results is directly proportional to the net force & had a magnitude that is inversely proportional to the mass; the direction of the acceleration is the same as the direction of the net force; "vector a" = "sigma vector F"/"m"; "sigma vector F" = "m"("vector a")
Term
 SI unit of force
Definition
 kg(m)/s^2 (Newton) (N)
Term
 external forces
Definition
 forces that the environment exerts on the object of interest
Term
 internal forces
Definition
 forces that one part of an object exerts on another part of the object
Term
 Is the newton a derived or base SI unit?
Definition
 derived
Term
 CGS unit for mass
Definition
 gram (g)
Term
 CGS unit of acceleration
Definition
 centimeter/second^2
Term
 CGS unit for force
Definition
 dyne (dyn)
Term
 BE unit for mass
Definition
 slug (sl)
Term
 BE unit for acceleration
Definition
 foot/second^2
Term
 BE unit for force
Definition
 pound (lb)
Term
 free-body diagram
Definition
 a diagram that represents the object & the forces that act on it
Term
 Only the forces that _____ appear in a free-body diagram
Definition
 act on the object
Term
 Newton's third law of motion/the "action-reaction" law
Definition
 whenever one object exerts a force on a second object, the second object exerts an oppositely directed force of equal magnitude on the first object; for every action there is an equal, but opposite, reaction
Term
 3 fundamental forces
Definition
 1. gravitational force2. strong nuclear force3. electroweak force
Term
 Newton's Law of Universal Gravitation
Definition
 every particle in the universe exerts an attractive force on every other particle; F = G(m1m2/r^2)
Term
 What does "G" (universal gravitational constant) equal in Newton's Law of Universal Gravitation?
Definition
 6.674 x 10^-11 N m^2/kg^2
Term
 What does "r" mean in Newton's Law of Universal Gravitation?
Definition
 the distance between the center of masses of the objects/particles
Term
 weight
Definition
 the gravitational force that the earth exerts on an object
Term
 SI unit for weight
Definition
 newton (N)
Term
 equation for weight
Definition
 W = G(ME x m)/r^2 OR W = m(g)
Term
 normal force (vector FN)
Definition
 the component of the force that a surface exerts on an object with which it is in contact that is perpendicular to the surface
Term
 When does FN = W?
Definition
 if an object is resting on a horizontal surface & there are no vertically acting forces except the object's weight & the normal force
Term
 Does the normal force always have the same magnitude of the weight of an object?
Definition
 no!
Term
 When does the apparent weight not equal the true weight?
Definition
 if the scale and the person on it are accelerating
Term
 apparent weight
Definition
 the force that an object exerts on a scale with which it is in contact
Term
 equation for apparent weight
Definition
 FN = m(g) + m(a)
Term
 frictional force (friction)
Definition
 the component of the force that is parallel to the surface when the object moves or attempts to move along a surface
Term
 maximum static frictional force (vector fsMAX)
Definition
 the force just before breakaway
Term
 equation for kinetic frictional force
Definition
 fk = uk(FN)
Term
 What is the main difference between static friction & kinetic friction?
Definition
 static: opposes the impending relative motion between two objectskinetic: opposes the relative sliding motion that actually does occur
Term
 equilibrium
Definition
 when an object has zero acceleration
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