Exam 2

Question 1

What was the ancient/Greek view of our solar system and the universe?

Answer 1

Earth was a sphere, everything orbited Earth

Question 2

Main contribution of Aristarchus?

Answer 2

Compared size of Earth to moon & sun. Sun was larger than Earth = we orbit the sun

Question 3

Main contribution of Aristotle?

Answer 3

Traveling south revealed different stars (Earth is round)

Question 4

Main contribution of Caesar?

Answer 4

Established leap years

Question 5

How did Eratosthenes measure size of Earth?

Answer 5

Distance between 2 cities

Question 6

Direct Motion

Answer 6

Planets move east

Question 7

Retrograde Motion

Answer 7

Planets stop & travel backwards (when first explained), caused by relative motion of Earth & planet

Question 8

Sidereal period

Answer 8

“True” period, viewed from space & 1 complete orbit

Question 9

Synodic period

Answer 9

Relative to the sun, viewed from Earth, but Earth is also moving in its orbit. Longer than sidereal.

Question 10

Galileo’s impact

Answer 10

Saw mountains on moon (not perfect sphere)
Sun has spots & rotates (able to view without damage)
Milkyway is not featureless, but a mass of stars

Question 11

Difference between speed & velocity?

Answer 11

Speed = time rate of object moving along path
Velocity = rate & direction of object's movement (acceleration)

Question 12

We is something accelerating?

Answer 12

If object is changing its velocity

Question 13

Mass vs weight

Answer 13

Mass: total amount of material in an object. More mass = more acceleration. Does not change, same everywhere
Weight: depends on affect of gravity, does change due to location

Question 14

What important quantity did Newton add when modifying Kepler’s Third Law?

Answer 14

Sum of 2 masses orbiting each other; Newton’s version could be applied anywhere, not just planets

Question 15

Escape velocity

Answer 15

Related to gravitational force; higher mass = higher velocity needed to escape. Lower mass = not enough atmosphere or mass to hold onto gasses, gasses moving too fast can escape.

Question 16

Finite speed of light

Answer 16

Olaus Romer discovered this by observing eclipse’s of Jupiter’s moons

Question 17

How did Newton show light was a spectrum?

Answer 17

By passing light through a prism

Question 18

What does light travel through in space?

Answer 18

Ether

Question 19

Magnetic field direction

Answer 19

Out from north (+) into south (-)

Question 20

Photoelectric Effect

Answer 20

Showed light is a particle and a wave

Question 21

Electromagnetism

Answer 21

Electro waves travel at speed of light = light is electro wave (Maxwell)

Question 22

Light is a wave

Answer 22

Young’s double-slit experiment, alternating light and dark bands

Question 23

Photons

Answer 23

Small packets of energy

Question 24

Spectral lines

Answer 24

Hundreds of dark lines dividing a frequency

Question 25

Continuous spectrum

Answer 25

Hot, opaque body (blackbody) or a hot, dense gas

Question 26

Emission line spectrum

Answer 26

A hot, transparent gas

Question 27

Absorption line spectrum

Answer 27

A cool, transparent gas

Question 28

Spectroscopy

Answer 28

Spectral lines provide reliable evidence about chemical composition of distant objects

Question 29

Doppler effect

Answer 29

Shifting of wavelengths due to movement of objects. Redshift = moving away (longer wavelength)
Blueshift = moving closer
Used with radar guns and any wavelength. Compared to what is measured to what it would be at rest.