Space Physics Lecture Notes - Flashcards

A comprehensive set of practice Q&A flashcards covering space basics, vacuum, momentum, Newton’s laws, rocket physics, propulsion options, gravity assists, atmosphere vs vacuum, gas pressure, breathing, and space sound.

What is the role of space in the semester’s topics according to the notes?

Space is laying the groundwork for every other topic we'll discuss this semester.

What are the key questions listed about space on Page 2?

What space is, how objects move through space, what vacuum is and if space is truly empty, whether there is sound in space, and the momentum of spinning objects.

How far away is Proxima Centauri, the nearest star?

About 4.3 light years.

If you traveled at 30 km/s, approximately how long would it take to reach Proxima Centauri?

About 43,000 years.

The 30 km/s speed used in the Proxima Centauri calculation corresponds to which natural speed?

Earth’s orbital speed around the Sun (about 30 km/s).

What is the approximate travel time to Proxima Centauri at 30 km/s, expressed in years?

Approximately 43,000 years.

In the NASA response time poll about Mark Watney, what range of times were offered as possible correct answers?

Options ranged from a few minutes to years; any of them could be considered plausible in the poll.

What are the two broad topics introduced on Page 5?

How objects move through space and how a rocket works.

What does Newton’s First Law state?

An object moves at constant velocity unless a net external force acts to change its speed or direction.

How is momentum defined?

Momentum p = mass × velocity (p = m v).

What does Newton’s Second Law relate net force to?

Net force equals the rate of change of momentum: F_net = Δp/Δt.

What does Newton’s Third Law state?

For every force, there is an equal and opposite reaction force.

What is the Conservation of Momentum in simple terms?

When objects interact, momentum can be exchanged, but the total momentum of the system is conserved.

How does a rocket gain upward velocity according to momentum conservation?

By expelling fuel downward at high speed, which increases the rocket’s upward velocity while conserving total momentum.

Why are multi-stage rockets used?

To shed mass (spent fuel tanks) as fuel is expended, making it easier to speed up, though it’s expensive.

Name three propulsion types mentioned in the notes.

Chemical rockets, high-pressure gas thrusters, and ion propulsion.

What is an alternative propulsion method discussed that uses light?

Light sails powered by photons (photons carry momentum).

How do light sails propel a spacecraft?

Photons reflect off a large mirror, transferring momentum and pushing the craft forward.

What is gravity slingshot (flyby) propulsion?

Using a planet’s gravity to gain speed, effectively trading momentum with the planet.

What does the notes say about “No swooping in space”?

In space there is no atmosphere to push against, so propulsion must come from expelling mass, not redirecting air.

How does Newton’s Third Law apply to flight in air?

A craft pushes air backward and the air pushes the craft forward with an equal and opposite reaction force.

What is gas pressure?

The force per unit area exerted by gas particles when they collide with surfaces (P = F/A).

What is vacuum, as defined in the notes?

An absence of matter, typically with no gases; vacuum itself doesn’t pull you in, but pressure differences matter.

What causes atmospheric pressure on Earth?

The weight of all the air above a given point.

How does atmospheric pressure change with altitude?

Higher pressure at lower altitudes; lower pressure higher up; no atmosphere means no pressure.

Why do winds occur around storms?

Air moves from high-pressure to low-pressure regions, causing wind.

Describe the basic sequence of breathing as given in the notes.

Expand ribcage and drop diaphragm (pressure in lungs drops, air flows in), then contract ribcage and raise diaphragm (pressure in lungs rises, air flows out); repeat.

What does the notes say about pressure under water and surfacing from depth?

Surfacing from depth doesn’t cause explosions; the same pressure principles apply as with vacuum versus sea level.

What is sound, as defined in the notes?

Waves of pressure; sound is the pattern of pressure changes over time.

How dense is the interstellar medium between stars?

About one gas particle per cubic centimeter.

How dense can gas be in the densest star-forming clouds?

About one million gas particles per cubic centimeter.

How many gas particles are typically in Earth’s atmosphere per cubic centimeter?

About 10^19 particles per cubic centimeter.

What space-based evidence provides an actual “sound” in space?

Pressure waves detected in the gas around a supermassive black hole in the Perseus galaxy cluster, via NASA’s Chandra observations (black hole sonifications).