Exam 1 Flashcards
What is the cosmic address?
Earth
Solar System
Milky Way
Local Group
Local Supercluster
Universe
What is a lightyear?
The distance light travels in one year
What is an Astronomical Unit?
The average distance between Earth and the Sun
Age of the universe
14 billion years
Age of the solar system
4.5 billion years
The Big Bang
The event thought to mark the birth of the universe
The early universe only contained what elements?
Hydrogen and helium
Most galaxies are moving _____ us.
away from
The farther away a galaxy is the _____ it is moving.
faster
What is the result of Hubble’s observations?
What does it show the universe doing?
The universe is expanding
What is the raisin cake analogy?
As a raisin cake expands, every raisin moves away from every other raisin, just as galaxies move away from each other in an expanding universe.
What is mass?
The amount of matter an object has
What is weight?
The amount of force that acts on an object
What causes weightlessness?
Falling without any resistance to slow you down (free-fall)
Newtons Laws of Motion
- An object moves at a constant velocity if there is no net force acting on it.
- force = mass x acceleration (F = ma)
- For any force, there is always an equal and opposite reaction force.
Universal Law of Gravity
- Every mass attracts every other mass through gravity.
- The strength of the gravitational force attracting any two objects is directly proportional to the product of their masses.
- The strength of gravity between two objects decreases with the square of the distance between their centers.
Fg=G(M1M2/d^2)
Types of Energy
- Kinetic
- Potential
- Radiative
What is the difference between thermal energy and temperature?
Thermal energy is the total kinetic energy of the many individual particles moving within a substance.
Temperature measures the average kinetic energy of particles in a substance.
Light acts like a _____ and a _____.
wave, particle
What is a photon?
a particle of light
How can light be described?
By its wavelength (meters), frequency (Hertz), and how much energy (joules) it has
All light moves at _____ speed.
the same (speed of light)
What are the parts of an atom?
electrons (outside of the atom)
protons & neutrons (inside of the atom)
What is atomic number?
the number of protons in an atom
What is atomic mass?
the combined number of protons and neutrons in an atom
What is an isotope?
forms of an element that have the same number of protons but different number of neutrons
What are the three types of spectra?
Continuous, emission, and absorption
How is an absorption spectrum formed?
An electron absorbs a photon of light and goes up a level.
An electron grabs light so it gains energy.
How is an emission spectrum formed?
An electron emits a photon of light and goes down a level.
An electron lets out light, so it loses energy.
The 7 regions in the electromagnetic spectrum
Gamma rays
X-rays
Ultraviolet
Visible
Infrared
Microwave
Radio
Blackbody spectra
What does it show?
Almost all objects emit light that approximates thermal radiation.
The temperature of an object can be determined by the peak of the ____ of the blackbody spectra.
wavelength
A hotter object will peak in the _____ end of the spectrum and a cooler object will peak in the _____ end of the spectrum.
blue, red
What is the Doppler effect?
the shift in wavelength due to movements towards or away from the observer.
The greater the Doppler shift, the _____ the object is moving.
faster
_____ means the wavelength is stretched longer because it is moving _____ the observer.
Redshift, away from
_____ means the wavelength is shortened because it is moving _____ the observer.
Blueshift, towards
The Voyage scale
The Sun is the size of a grapefruit and all the planets are much smaller. Four planets are within 20 m of the sun, and the rest are spread much farther apart.
If we imagine the history of the universe compressed into one year, with the present as the stroke of midnight at the very end of that year, dinosaurs became extinct _________.
yesterday morning
We can put the 14-billion-year age of the universe into perspective by imagining this time compressed into a single year, so each month represents a little more than 1 billion years. On this cosmic calendar, the Big Bang occurred at the first instant of January 1 and the present is the stroke of midnight on December 31.
Suppose that the Sun shrank in size but that its mass remained the same. What would happen to the orbit of the Earth?
Earth’s orbit would be unaffected.
The force of gravity between Earth and the Sun, and hence the orbital distance and speed of Earth, depends only on the Sun’s mass (and the Earth-Sun distance), not on the Sun’s size.
What is Newton’s version of Kepler’s third law?
The greater mass of the star would mean a stronger force of gravity at any given distance, which in turn would mean a higher orbital velocity
The orbital period of a small object orbiting a much more massive object depends only on its orbital distance, not on its mass
