# Shared Flashcard Set

## Details

Ch 7 Linear Momentum
Concepts and Formulas
22
Physics
10/14/2012

Term
 linear momentum  of an object is defined as
Definition
 The linear momentum 'p' of an object : is the product of its  mass & a velocity  ex. a faster & heavy truck has  MORE momentum than a small moving car aka it takes MORE force to stop the truck than the car.
Term
 Formula for momentum
Definition
 →          → p =   m v   where : p : momentum (a vector) v: velocity (m/s) m: mass (kg)
Term
 Momentum  is a vector and points in the _____ direction as the _______ vector.
Definition
 same, velocity
Term
 One can also say that the momentum vector is _______ to the velocity vector, if the momentum vector ______ if the velocity vector doubles.
Definition
 directly proportional, doubles
Term
 A _____ is required to increase, decrease, or change  the direction of momentum
Definition
 force
Term
 relate momnetum to Newton's second law
Definition
 the rate of change of momnetum of an object is equal to the net force applied to it.
Term
 Give equation that relates momentum to Newton's second law
Definition
 ΣF=Δp/Δt sum of forces= change in mommentum/change in time same as  ΣF=p final - p inital/Δt same as   ΣF=mv2- mv1/Δt
Term
 Momentum is a ______ quality
Definition
 conserved,  momentum is same before and after a collsion etc.. 'the total momemtum of an isolated system of objects remains CONSTANT
Term
 Equation for conservation of momentum (such as 2 objects colliding)
Definition
 mA vA  + mB vB = mA vA  + mB vB
Term
 In a given system, momentum will always be conserved if _____
Definition
 no external forces are present ex. friction, gravity
Term
 Conceptual  Example 7-5: An empty sled is sliding on frictionless ice when Riley drops vertically from a tree above onto the sled. When she lands, does the sled speed up, slow down, or keep same speed?  B. What happens if Riley falls sideways off the slide?
Definition
 A. Speed decreases fall vertically: no inital horizontal momentum, so the total  horizontal momentum is equal to the momentum of sled intinally. b/c sled has more mass, the speed decreases B. SAME speed b/c momentum is conserved
Term
 Impulse formula
Definition
 impulse (Δp) = force • Δt unit: Newtons/ seconds
Term
 Impulse Definition
Definition
 is equal to the total change in momentum
Term
 a collision in which the total kinetic energy is called an
Definition
 elastic collision KEf= KEi
Term
 give equation for a totally elastic collision
Definition
 1/2m1v1+1/2m2v2=1/2m1v'1 + 1/2 m2v'2   where v' is velocity after collision (recall ke is 1/2 mv)
Term
 Give equation for v'1 in elastic collision
Definition
 v'1 =  (m1-m2/ m1 + m2) x V1
Term
 collisions in which kinetic energy is NOT conserved is called?
Definition
 inelastic collision
Term
 In a totally elastic collision what happens to the objects
Definition
 they collide & go off in seperate directions
Term
 In a totally inelastic collision what happens to the objects
Definition
 they collide & STICK
Term
 In a totally inelastic collision what is conserved?
Definition
 momentum & ofcourse TOTAL energy as always    *energy not created or destroyed
Term
 Give equation for inelastic collision
Definition
 (m1+m2)vf = (m1+m2)vi
Term
 Give components of theta for: x axis y axis flat & incline
Definition
 FLAT X: cosθ y: sinθ INCLINE X:sinθ Y:cosθ
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