Acceleration, Free-Fall, Early History

Question 1

equations to know

Answer 1

v = >d/>t a = >v/>t df = di + vt OR >x = vt vf = vi + at OR >v = at >x = 1/2 (vi + vf) t OR df = di + 1/2 (vi + vf) t >x = vi t + 1/2 a t2 OR df = di + vi t + 1/2 a t2 vf2 = vi2 + 2ax ht(down/up) = [2x/a ht(down&up) = 2[2x/a

Question 2

freefall

Answer 2

when an object falls under the influence of gravity alone

Question 3

gEarth = ?

Answer 3

-9.81 m/s2

Question 4

What lesson did scientists have to relearn?

Answer 4

They had to relearn that our perception of motion can be influenced by how we observe it.

Question 5

acceleration

Answer 5

how velocity changes over time

Question 6

Explain or demonstrate why the unit for acceleration is m/s2

Answer 6

The units are m/s2 because acceleration is the change in velocity over time/per unit time. Velocity has fundamental units of m/s and time has fundamental units of s, so acceleration = change in velocity/change in time yields units of m/s/s. This yields m/s2 as shown below: m/s/s = m/s . 1/s = m/s2

Question 7

celestial bodies

Answer 7

refer to those things we see beyond the earth, in the “heavens”. moon, sun, planets

Question 8

What do some of humankind’s earliest recorded observations of motion concern?

Answer 8

concern cycles of sun, moon, stars - daily cycle of sun, 28 day cycle of moon, nightly & seasonal cycle of stars

Question 9

Instead of a sci analysis, how were the movements of celestial objects explained?

Answer 9

based on religious ideas or primitive analogies with the kind of motions they observed around themselves. Ex: Greeks thought the Sun was a god who rose out of the ocean and drove a chariot across the sky.

Question 10

When were the 1st telescopes invented?

Answer 10

17th century (1600’s).

Question 11

What were the early Greeks responsible for? and when?

Answer 11

began developing systems of thought that explained phenomena according to empirical/logical principles vs. religious ideas. 5th & 6th century BC.

Question 12

two early Greek philosophers

Answer 12

Thales of Miletus & Pythagoras.

Question 13

Who developed the Greek understanding of motion? When?

Answer 13

Aristotle. 384-322 BC. Athens.

Question 14

For how long did the Greek understanding of motion dominate Euro thought abt motion?

Answer 14

more than 1000 years

Question 15

Aristotle’s understanding of motion

Answer 15

I. All objects have a tendency to move toward their “natural” place, depending on what they are made of (earth, water, air, fire) II. The Earth is at the center of the universe & doesn’t move. Sun, Moon, & planets moved in perf circles around earth (constant distance, speed, & direction) III. speed of obj’s to/from earth depended on weight IV. any obj set in motion, on the earth & any rate, will eventually slow & stop. force necessary to keep it moving.

Question 16

On what was Aristotle’s understanding of motion based?

Answer 16

observations. logic & empirical principles.

Question 17

problems with Aristotle’s ideas

Answer 17

With observ, obvious tht the planets were sometimes closer to Earth than at other times & tht they moved in their orbits @ varying speeds.

Question 18

How did Ptolemy try to make the observations of celestial motion fit Aristotle’s theory or explanation of motion?

Answer 18

epicycles. said the planets also revolving in mini orbits. (include diagram of epicycles upon epicycles)

Question 19

What did epicycles explain?

Answer 19

retrograde motion. planets appeared to move backwards sometimes.

Question 20

benefits of Ptolemaic system

Answer 20

explained curious motions of the planets.

allowed for the prediciotn of the future positions

Question 21

role of the Catholic church in promoting Ptolemy’s & Aristotle’s understanding of the structure of the universe

Answer 21

regarded by Church as “authorities” who, tho they lived in the pre-Christian era, had put foward doctrines that contained divine wisdom. scholars who questioned these authorities might have publications of their books prohibited, or even been imprisoned/executed

Question 22

Why were philosophers, scientists, & Christian scholars distrubed by Ptolemy’s system (geocentric w/ planets orbiting on 1/more epicycles)?

Answer 22

made the system jury-rigged, like a clunky machine fitted out w/ additional parts just to make it work properly. lacked the elegance & simplicity that even the Christian scholars thought God’s work should reveal.

Question 23

Who was William of Ockham, when was he alive, and what was his important philosophical & scientific principle?

Answer 23

Franciscan monk & Oxford scholar. 1285-1349. “entities must not be needlessly be multiplied”

Question 24

Ockham’s/Occam’s razor

Answer 24

when consdiering competing explanations, one chooses the simplest explanation (the one w/ the fewest assumptions) & is supported by evidence. when considering an explanation, u should suspect that it’s false if it needs assumption/extra parts added to it over time to fit new data.

Question 25

What was Copernicus’s insight into the prob of retrograde motion & the reason y the Ptolemaic system was failing to accurately predict planetary positions?

Answer 25

retrograde movement of Mars occurs cuz has larger orbit than earth, so earth sometimes passes it, making it look like it’s going backwards. from view of observer.

Question 26

what aspects of ptolemy/aristotle’s system did copernicus retain in his heliocentric system?

Answer 26

didn’t challenge the other Ptolemaic ideas of how planets moved at constant speeds & in perf circles. to explain, had to retain some of the epicycles.

Question 27

What did Kepler (1571 - 1630) realized abt the orbits of the planets around the sun?

Answer 27

The planets moved in elliptical, not circular, orbits. The planets moved faster the closer they were to the sun & slower the farther away cuz Sun exerted some sort of force.

Question 28

effect of Kepler’s Laws of Planetary Motion?

Answer 28

had provided the math. foundation for the acceptance of the Copernican theory of solar system. now positions & movements of the planets could be calculated with a high degree of accuracy.

Question 29

why did heliocentric view seem absurd to some people

Answer 29

If Earth was indeed moving thru space @ incredible speeds and spinning on axis, y don’t we feel the motion/fall off?

Question 30

What did Galileo demand of his students?

Answer 30

that they test their ideas thru experimentation & empirical observation

Question 31

Galileo’s procedure for testing Aristotle’s ideas of motion?

Answer 31

used his pulse (& other mechanisms such as water clocks) as a timer, and rolled objects of diff weights down inclined planes.

Question 32

What did Galileo find in testing Aristotle’s ideas abt motion?

Answer 32

1) All objs near surface of earth fall @ same rate of accel, regardless of weight.
2) force not required 4 motion. force doesn’t cause motion –> causes changes in motion.

Question 33

what argument did galileo use to defend heliocentric view?

Answer 33

sailors on a ship can’t feel ship’s motion when moving at constant speed on calm sea

Question 34

in which book did Galileo put forth his argument?

Answer 34

Dialogue on the Two Chief World Systems, 1632

Question 35

who was born same year galileo died?

Answer 35

Isaac Newton (1642-1727).

Question 36

Galileo’s Law of Falling Bodies

Answer 36

cumulative distance fallen is proportional to the square of time, and the distance fallen b/w each successive time interval increases according to the progression of odd numbers

Question 37

contributions of Galileo

Answer 37

1. all obj’s near suface of earth fall @ same rate of accel regardless of weight
2. After initial impulse, an obj might move forever until opposed by another force (inertia)
3. total distance fallen is proportional to t²
4. the distance fallen b/w each successive time interval increases according to the progression of odd numbers
5. telescope & movement & surfaces of celestial bodies
6. precise measurements to test ideas