Momentum, Machines, and Radioactive Decay Flashcards
momentum
=mv, moving object’s tendency to continue along its present path
momentum of an isolated system is always ____
conserved, momentum of center of mass of an isolated system is constant in direction and magnitude
elastic collision
collisions where the mechanical energy is conserved, no energy dissipated to internal energy
inelastic collisions
when colliding objects lose some of their mechanical energy to internal energy
momentum(i) = momentum(f)
impulse
change in momentum, force of collision multiplied by duration of collision
average force on either colliding body
J = F(avg)delta(t) delta(mv) = F(avg)delta(t)
ideal machines…
reduce the force but don’t change work
half-life
length of time necessary for one half of a given amount of a substance to decay
alpha decay
alpha particle= helium nucleus
alpha particle is lost
beta decay
expulsion of an electron
beta particle = electron or positron
not the destruction of e-, the creation of an e- and a proton from a neutron
positron emission
emission of a positron when a proton becomes a neutron
electron capture
capture of an e- along with the merging of that electron with a proton to create a neutron
proton destroyed and neutron created
gamma ray
high frequency photon, no charge, does not change the identity of the atom from which it is given off
gamma ray emission
often accompanies the other decay types
when an e- and positron collide
rest mass energy
E = mc^2
latent energy within the mass of an object
only if mass is created or destroyed
mass defect
nucleus has less mass than the sum of the masses of its individual parts
fusion
combining of two nuclei to form a single heavier nucleus
fission
splitting of a single nucleus to form two lighter nuclei
