Conservation Laws

Closed system

A system in which no forces are applied to the system

conservation law

statement that tells us that in a closed system there is a property that remains constant.

Energy

The ability to do work or cause change

Kinetic energy

the energy an object has due to its motion

Hooke's Law

Extension is directly proportional to force until the spring reaches it's elastic limit

Ideal Spring

obey's hooke's law because it experiences no internal or external friction

Spring constant

how hard it is to stretch a spring, measured in Newtons/meter

Center of mass

the dot in a free body diagram, we pretend all mass in an object is concentrated here

collision

when two objects hit each other

inelastic collision

a type of collision in which the kinetic energy after the collision is less than the kinetic energy before the collision

elastic collision

collision in which there is no net loss of total kinetic energy

contact time

how long two objects are in contact during a collision

Explosive collision

One object breaks into multiple pieces. Mechanical energy is not conserved, it is gained in this type of collision. Momentum is conserved.

Impulse

change in momentum, measured in Joules or Newtons/sec

Impulse-Momentum Theorem

The impulse on an object is equal to the change in its momentum

Law of conservation of momentum

law stating that the total momentum of a system does not change if no net external force acts on the system

linear momentum, total momentum

mass x velocity, p

Newtons/seconds

units of momentum

Impulse equation

J=Ft, J=Pfinal - Pinitial

Impulse

Area under a graph of Force vs time

momentum

_____________________ is conserved in all collisions

kinetic

__________________ energy is conserved in elastic collisions, but not in inelastic collisions

completely inelastic collision

special case of inelastic collision where the objects stick together during the collision. Momentum is still conserved, but objects have the same velocity after the collision.