impulse and momentum

momentum

The tendency for an object to KEEP MOVING – inertia in motion

Is Momentum a scalar or vector quantity?

Vector! Velocity is used to calculate it, and magnitude is taken into account

Momentum is _____ proportional to both MASS and VELOCITY!

directly

impulse

Change in momentum – when a force is applied to an object over time.

Does momentum and impulse have the same

units?

YES! A N•s is THE SAME unit as a kg•m/s!

the Impulse-Momentum Theorem

Any impulse on an object will change its momentum

A large impulse occurs when a large force acts in a ____ time or a small force acts over a ____ time

short, longer

an object which is moving at a ______ speed has momentum

constant

two objects of different mass are moving at the same speed; the more massive object will have the GREATER ______

momentum

impulse is a _____ quantity

vector

“subject to the force of gravity” meaning? impulse?

gravity is pulling it DOWNWARDS.. Impulse is NEGATIVE

an object’s momentum varies _____ with its speed

directly

if an object has momentum, then it also as ____ ___

mechanical energy

2 objects with different mass have the same momentum.

The ____ one will have the GREATEST ___ __

smaller, kinetic energy

objects involved in ____ encounter ____

collisions, impulses

an object that experiences a net impulse will experience a _____ ___

momentum change

in a collision, the net impulse experienced by an object is _____ to its momentum change

equal

two colliding objects will exert ____ forces upon eachother even when their mass is different

equal

a collision has an object encounter an ____ and a ____ __ ____

impulse, change in momentum

a particular collision lies along the contiuum is dependant upon the amount of ____ __ that’s conserved by the two objects

kinetic energy

elastic collisions occur when the collision force is a _____ force

non-contact

In an inelastic collision, some of the kinetic energy is converted into other forms of energy like:

sound, light, thermal energy, etc.

the ____ a ball rises upon collision with the ground when dropped, the ____ elastic that the collision is

higher, more

for increased momentum, ____ force is applied for as long as possible

greater

is more or less contact time good?

MORE

the force or impulse must be exerted on the object by something ____ the object

outside

if no outside force is there, there is __ change in momentum

NO

system

a defined collection of objects

closed system

No objects enter or leave (no gain/loss of mass)

isolated system

No external forces act on system (or the net = zero)

Law of Conservation of Momentum

the momentum of any closed, isolated system does not change –the number of objects does not matter, as long as no objects enter or leave the system and there is no net external force on the system.

internal forces

-forces between objects within a system
-CANNOT change the momentum of a system

external forces

forces exerted from outside a system

elastic collisions

-collisions in which both momentum and kinetic energy are conserved

-The total system kinetic energy before the collision equals the total system kinetic energy after the collision

inelastic collisions

-total system kinetic energy is not conserved (momentum IS conserved!)

-The total kinetic energy before the collision is not equal to the total kinetic energy after the collision

-A large portion of the kinetic energy is converted to other forms of energy such as sound energy and thermal energy

-sum of KE is reduced

are many collisions are either completely elastic or completely inelastic?

no!

when no external force is acting, the momentum of the system is ____

conserved

which quantities do not always occur in equal and opposite pairs when an interaction takes place within a system?

accelerations

2 ways impulse can be increased

1) increasing the force’s size

2) increasing the amount of time the force is acting

airbag problem 14

the airbag slows the driver’s forward momentum so that the same forward force is SPREAD OUT over a LONGER TIME INTERVAL