our dynamic universe Flashcards
newtons 1st law
object will remain at rest or at constant speed in straight line unless acted on by an unbalanced force
newtons 2nd law
when forced acting on an object are unbalanced, objects will accelerate in direction of unbalanced force
F= ma
newtons 3rd law
if object A exerts force on object B, then B exerts equal but opposite force on A
equation for weight, mass, and gravity
W= mg
weight parallel to slope formula
W= mgsinθ
weight perpendicular to slope formula
W= mgcosθ
equating energy work to potential and kinetic
Ew= Ep-Ek
equation for lifting object from ground
Ew= Ep
conservation of momentum formula
m₁u₁ + m₂u₂ = m₁v₁ + m₂v₂
what is the doppler effect?
change in frequency observed when a source of sound, or light, waves move relative to an observer
what happens when sound approaches an observer?
more sound waves received per sec (shorter wavelength)
frequency heard increased
what happens when sound moves away from an observer?
fewer sound waves received per sec (longer wavelength)
frequency heard decreased
what is redshift?
light from stars or galaxies moving away from us is shifted to longer (more red) wavelengths
what does a negative redshift value mean?
blueshift
how to calculate distance in light years?
distance/ 1 light year
how to calculate 1 light year?
365x24x60x60 (3x10⁸)
current estimate for age of universe
13.8 billion
what is dark matter?
matter in galaxies we cant see
evidence for dark matter
stars on outer arms of galaxies should travel slower than those closer to galactic core as they are further from centre of mass and experience smaller gravitational force of attraction
observations found orbital speed of stars on these parts to be moving much faster than expected for the mass that is visible to us
what is dark energy?
recent observations of redshift of distant galaxies shows universes rate of expansion is increasing
this contradicts idea that gravity is an unbalanced force acting to slow expansion down
-suggests unknown force acting against gravitation attraction, pushing matter apart
what is the big bang theory?
rapid expansion from a singularity
6 pieces of evidence for big bang theory
hubbles law
cosmic microwave background radiation
temperature of universe
surface temperature
olbers paradox
larger number of galaxies showing redshift than blueshift
gravitational force of attraction
6.67x10-¹¹
