Astronomy First Test

Question 1

1a three vector properties

Answer 1

acceleration, velocity, force

Question 2

1a three non-vector properties

Answer 2

mass, energy, electrical charge

Question 3

1b descriptions

Answer 3

velocity: change in position over time
acceleration: change in velocity over time
force: push or pull

mass: resistance to acceleration
energy: ability to do work
electric charge: + or - charge on an object, called q

Question 4

2a angular momentum

Answer 4

MVR = M’V’R’
remove mass, and assume that both radii are 1
1 * V = 1 * V’
Main velocity is 1, multiply second radius by 1.02
1 = 1.02 * V’
1/1.02 = V’

Question 5

2b vector addition and subtraction

Answer 5

transform second vector onto end of first, direction from there depends on vector arrow and + or -. sum of vectors is where the two together end up.
draw with ruler and show transformation.

Question 6

3a newtonian telescope

Answer 6

f = F/A. M = Fo/Fe. remember: use a little star as the image, don’t bother reversing. eye is right on eyepiece. The length of the tube is the Fo - half of aperture, cause light bounces out of the tube and the primary image is at the focal length. Eye is right on eyepiece. It is normal for eyepiece lens to take crossed beams and infinitize them.

Question 7

5a why is interferometry useful

Answer 7

Interferometry is combining more than one radio telescope to gather data. Combining data from more than one telescope effectively creates one telescope as large as the distance between the telescopes involved. This allows for much greater resolution and smaller beam width when studying the sky.

Question 8

4a EM wavelength

Answer 8

make a new deck

Question 9

4b why are radio telescope dishes so big

Answer 9

The energy of a EM wave varies inversely with its wavelength. This means that radio waves are low energy and faint, and a large reflecting surface is needed to get enough data out of them.

Question 10

5b adaptive optics

Answer 10

Adaptive optics is when a reflecting mirror is made of many small individual mirrors that can be adjusted. They are adjusted to counter atmospheric turbulence and thus gain a much sharper image.

Question 11

6a kepler’s 3 laws

Answer 11

1. A planet orbits the sun in an ellipse with the sun at one focus
2. a line joining the planet and the sun sweeps over equal areas during equal amounts of time
3. The square of the orbital period is directly proportional to the cube of the semi-major axis.

Question 12

6b ellipse diagram

Answer 12

Diagram Needs:
Ellipse, sun, 4 planets, shaded between planets, center marked, C and a marked below it, written defintion of E w/ e=C/a, peri and aph marked and w/ slowest/fastest label. Show that areas are equal

Question 13

7a prove earth rotates

Answer 13

coriolis effect: Geometry of the rotation of earth deflects massive objects to appear to turn clockwise in northern hemisphere and counterclockwise in southern hemisphere.
focault pendulum: As the earth spins on its axis, a pendulum not restricted to one plane will precess and change its plane

Question 14

8a prove earth rotates around sun

Answer 14

stellar paralax: apparent position of star changes as earth moves around the sun
stellar aberration: telescopes on earth need to aim a bit ahead of the true position of the star in the direction of earth’s orbital velocity