Physics

• Cause direction and/or speed of motion to change
• During an acceleration, size of velocity or direction of motion change.

What are the 4 forces of nature?

• Gravity
• Electromagnetic
• Strong Nuclear
• Weak Nuclear

Inverse square laws mean that quantity decreases with square of distance from source, such as gravity.

Four basic states of matter:

• Solids: particles barely moving, cool temperatures
• Liquids: Atoms in close contact, but chains of atoms moving, warmer than solid
• Gas: Individual atoms move freely. Large space between particles (or hot)
• Ionized gas: "Plasma" Electrons so energetic that they're easily ionized. Very hot

Some important definitions Thermal spectrum: All atoms and molecules in constant motion, so therefore emit thermal specradiation. This at same temp emit same thermal spectrum.

• Emission lines: Atoms go to lower energy state w/emission of photon. Atoms need prior energy source to have excited electrons
• Absorption lines: Photon absorbed and atom rises to higher energy state. Need unexcited gas with bound electrons and background light source.

Surface brightness: Luminosity per area

Limiting resolution (or resolving power): smallest angular separation you're capable of detecting. the further away you are, the less separation you see.

• Apparent magnitude: Exactly how bright something appears in the sky.
• Excatly how bright some object is when measured from standard distance of 10 pc

1. Write this number using scientific notation: .000463
   
2. A spaceship is headed directly towards the sun at 10 m/s. It suddenly makes a left-hand turn, continuing at 10 m/s. The ship experienced a change in
   
   1. velocity
      
   2. speed
      
   3. luminosity
      
   4. gravity
      
   5. none of the above
      
3. If you had a hunk of aluminum at 20000 K, what phase of matter would you expect it to be?
   
4. If Greg has a single short Americano at 80 C, and Marcel has a single grand Americano at 80 C, which has more energy? Why?
   
5. Two objects in space have the same luminosity, but one object is twice the size of the other. Which object has higher surface brightness?
   
6. Where sould you put a cool gas in order to obtain an
   
   1. absorption spectrum?
      
   2. emission spectrum?