lecture 2

Question 1

What are some noticeable changes to spaceflight within the last 5 years and why?

Answer 1

there is an increased frequency of “private” flights in low earth orbit
- cost of flying has decreased
- increase of individuals who flew into orbit
- more “space tourists” are travelling into space (space x’s dragon and falcon 9)

Question 2

What are some characteristics of SpaceX’s falcon 9? What is falcon 9 planning to become?

Answer 2

• falcon 9 is a 2 stage vehicle
• uses liquid fuel

It is becoming reusable
- first stage is already reusable (returns from soft landing)
- second stage will eventually become reusable on its successor ship

Question 3

name some Space X facts

are they working with anyone? what do they do in space?

Answer 3

• Space X is completely independent of any other space exploration organization
• When astronauts from Space X go into orbit, they combine a tourists experience with science exploration activities; different than blue origin (just tourisim)
• want to be going to and from the moon regularly in 2026

Question 4

what is the “polaris dawn” mission?

purpose, whats going to be done,

Answer 4

polaris will see a human crew fly higher (1400km) into orbit than anyone since apollo 17 in december 1972
- space x engineers are going to test new space suits by conducting a private space walk (first space walk not associated with NASA)

• the purpose is to test suits + explore newer unkown area in space
• investigating area past the van allen belt (protects earth from radiation); can be dangerous to investigate how significant solar flares are

Question 5

What is a solar flare?

Answer 5

the sun emitting flares, prominencesm and coronal mass ejectings
- increases the amount of radiation that goes towards the earth; the sun blasting us
- sun goes through 11-year cycle; gets progressively more “aggressive”

geomagnetic storm
- solar flares are the causes northern lights (auroras)
- charged particles from the sun sweeping acorss enviornment
- radiation colliding with oxygen causes the light to be emitted; is safe to view
- too much = overwhelemd electrical machines; power outtages
- cannot predict when it occurs
- easier to see where light pollution is minimal

Question 6

How are we not harmfully effected by solar flares?

Answer 6

earths atmosphere is able to deflect most of the harmful radiations that the sun barells towards us
- magnetosphere and Van Allen radiation belt protects us from solar flares

Question 7

Who was Galileo

what did he do, what did he discover

Answer 7

Galileo realized that dropping a feather and a hammer on the moon will allow them to hit the surface at the same time
- doesnt happen on earth because a feather gets displaced by the wind because of its small mass
- no air (atmosphere) = same acceleration

used the scientific method (experimentalist)
- allows science to progress

utlilized a telescope (refracting telescope)
- observed moon and sun; he went blind
- observations proved kelpers law; heliocentric universe
- observed venus’ phases

Question 8

What is the scientific method? Why do we use it?

Answer 8

identify problem → gather data → hypothesis → experiment (test hypothesis) → does the data agree (yes=repeat experiment) (no=create new hypothesis)

we use it
- to allow science to progress
- to allow other scientists to conduct the same experiment with same results

Question 9

What are laws of nature?

Answer 9

• laws that nature plays that apply to the universe
• theories can be updated/changes upon new information

Question 10

How to use scientifc notation

provide an example

Answer 10

very large/small numbers that need to be expressed in an easier way
- make the number have 1 number before decimal
- coefficient shows how many spots over you moved the decimal
- negative = right
- positive = left

example
- 0.038 = 3.8 x 10^-2 (moves decimal 2 spots right)
- 422 = 4.2 x 10^2 (moves decimal 2 spots left)
- 9.975 = 9.975 x 10^0 (doesnt move)

Question 11

What are the system international standard set of units?

Answer 11

time = seconds (s)
mass = kilograms (kg)
length/distance = meters (m)

always write the unit

Question 12

Why are units so important?

what happened in the disaster without documented units

Answer 12

• NASA mission to mars 1999 “climate observer”
  
  • one team handled the cruise phase
    
    • needs to be perfect to get there
  • one team used SI units, the other did not.
    
    • they basically had the wrong distances and speeds
    • caused satellite to crash
      
      • its in pieces on the surface of mars; slammed into mars instead of going into orbit
      • NASA was embarrassed
    • career ending for these individuals
      
      • everyone involved now has to look for something else
      • lost half a billion dollars

Question 13

How did Issac Newton impact the science community?

what he did, how it impacted, how we still use his laws

Answer 13

• discovered gravity
• used scientifc methods
• his laws were a subset from theory of relativity
• laid the foundation for physical science
• his laws still apply to this day

Question 14

What is Newtons first law?

law of intertia

Answer 14

Newtons first law (law of inertia)
- every object will continue to be in a state of rest/constant speed unless changed by an outside force
- a box will not move unless something moves it; its intertia is happy
- something that was thrown would continue to fly if gravity (an outside force) did not exist

an objects momentum (P), doesnt change unless acted upon an outside force
- P = mass x velocity (kg.m/s)
- when we have momentum, we continue as is as long as momentum doesnt change

On earth, outside force is wind (friction) so momentum is constantly impated
In space, there is not friction, therefore momentum remains untouched

Question 15

What is Newtons second law?

Answer 15

the change of motion of a body is proportional to and in the direction of the force acting on it
- going 100km on the highway = momentum (first law)
- tapping on the breaks is an external force
- generating friction between brake pads, and your car
- you are experiencing acceleration
- if you slam on the brakes, you feel yourself moving forward despite the car slowing down; you want to keep moving
- applying a significant amount of force opposite of where youre going, you get pushed back bc of seatbelt
- external force has been applied and you momentum changes
- whatever direction the force applies, that the direction the acceleration is applied

amount of acceleration is dependant on the mass
- small mass + a lot of force = a lot of acceleration
- big mass + a lot of force = smaller acceleration
- speed changing means momentum is changing

F = m x a
- F = net applied external force
- m = mass in kg
- a is the acceleration (m/s^2)
- rate of change of an objects momentum

Question 16

What is Newtons third law

action reaction

Answer 16

for every action there is an equal and opposite reaction
- the mutual actions of two bodies upon each other are always equal in strength and act in opposite directions
- action and reaction
- youre sitting on a chair, the chair is pushing back in you; chair doesnt want to collapse so it pushes back
- consequence is you not moving
- shooting a gun; recoil

this allows rocket flight
- force by the exhaust in other direction, pushing rocket down
- there is an opposite force in the other direction pushing the rocket upwards; momentum aimed in the other direction, rocket goes up, exhaust goes down as long at the force applied doesnt change

Question 17

How does gravity work?

Answer 17

gravitational attraction between two bodies must be proportional to their masses
- the more mass, and the closer you are, the stronger the pull of gravity
- apple falling scenerio; Newton recognized the apple falling was under the same gravitational force the moon was subjected to while orbitting the earth

gravity is an attractive force
- like magnets except only attractive
- gets weak over long distances, but never disappears

F = G(m1m2) / R^2
- F (newtons)
- m (kilograms)
- R (meters)
- G (universal gravitational constant)

Question 18

What is the inverse square law?

Answer 18

the further you get from a source, the singal spreads as the square of the distance
- applies to light, gravity, and electrostatics
- light gets dimmer the further away it is
- if you double the distance from a source of radiation, the intensity decreases by a factor of ^2

example
- start with a distance of 1
- second distance is 1/4
- third distance is 1/9

Question 19

What did Newton use from Keplers theories?

Answer 19

newton found a more general form of P^2 = a^3 (used for ellpise)

• P^2 (M1M2) = a^3
• p (years)
• a (astronomical units)
• M1M2 (sum of the masses of the two objects that were gravitationally attracting eachother

Newton realized Kepler saw a profound relationship between orbital period and distance between the two objects that were gravitationally bound
- P^2 = 4 pi^2 (a^3) / G(M1+M2)
- objects are always in attractive mode; everything is attracted to everything
- allows us to look at any object orbitting sun; even exoplanets

Question 20

Who is Edmund Halley?

Answer 20

lived in the 17th/18th cenutry

utilized the planet orbit formula to figure out that a comet orbits around the sun
- using keplers general 3rd law
- never lived to see return of his comet; was named after him
- was a small comet
- will return in 2062
- used scientifc method to verify his comet behaved as other planets did

Question 21

weight and gravity

how it changes because of gravity/lack there of

Answer 21

mass is an intrinsic quality; it applies only to you
- weight is not
- you would still weigh the same now as you do in orbit

the gravitational force of attraction that your mass experiences depends on the gravitational acceleration between you and the object you are on
- your weight is a measurement of your intrinsic mass on this gravitational field; weight = mass x gravitational acceleration
- weight is a mass’s response
- weight = mass x gravity
- force = mass x acceleration

everything accelerates towards the ground because of gravity
- result of mass and radius of our plent

objects in space still feel earths gravitational pull

Question 22

Why do astronauts feel weightless?

Answer 22

objects in orbit around the earth still experience gravitational attraction towards earth
- astronauts in orbit have a motion more or less parallel to the earths surface

objects in orbit are falling around the earth; thus astronauts feel weightless
- they are being pulled towards center of earth, but speed allows them to go around the center and be in orbit

Question 23

What are the effects of staying in orbit for a longer period of time?

weightlessness

Answer 23

physiological changes
- bad motion sickness; goes away eventually
- calcium depletion; bones weaken
- muscles lose strength; not fighting gravity
- eyeballs lose shape; different pressure

many astronauts spend 3-4 hours daily working out to negate these effects

Question 24

Why do people weight differenly in different places?

different planets

Answer 24

mass doesnt change, weight does
- different places; different gravitational accelerations

other forces
- electromagnetic forces
- electric charges magnetism
- positive and negative
- rubbing your feet on a carpet and zapping someone
- static charge
- north/south pole (attractive and repulsive forces)
- frictional forces
- allows us to walk and drive
- friction between you and the ground
- atmospheric drag
- parachute
- allows you to slow down before you hit the ground

Question 25

What is Density? (p)

Answer 25

the amount of material that exists within a given volume
- p = mass / volume
- utlizes keplers third law

can determine mass by looking at its orbital perimeters
- if you know mass, you can measure density and
- volume

example
given a sphere of ice
- measure the diameter of it
- determine mass
- can determine density

Question 26

liquid vs solid density

Answer 26

liquid
- anything that has a lower density will float
- anything that has a higher density will sink

**solid (metal) **
- lower density means less metals, more rocks
- higher density means more metals, less rocks