HPS250H1 Lecture : 6th Feb 2012.doc

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maroonmammoth349

3 May 2012

School

UTSG

Department

History and Philosophy of Science and Technology

Course

HPS250H1

Professor

Hakob Barseghyan

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Document Summary

Carrying on from last lecture: (the basic points of) logical positivism: The experience would be laden with the theory. There is an apple in front of me cannot be a pure observational statement. Not all sensations are trusted, we still need some filtration. And so, the question is how to live with theory- ladeness. The logical positivists tried to find a set of absolutely trustworthy observational statements, and thus to build up science (ie. scientific knowledge) which was the wrong approach. There are 2 types of theories (in our world): And generalized propositions which we ascribe meaning to. 2 propositions can be saying the same thing (be equivalent) But in fact theey are not equvalent, it is just because of the statistics. Their aim is to understand the underlying mechanism of the process. We have singled out this question, and it will take the scientists of coming generations to solve it. What is intolerable is to assign probabilities to observations.

Related Questions

2. Which of the following statements accurately describe the relationship between science and technology?

⬤ Technology and science are the same thing, and achieve the same goals.

⬤ The knowledge gained from science helps humans develop technology.

⬤ Improvements in technology can allow for better scientific observations.

⬤ Science and technology both use the scientific method answer questions.

⬤ Technology allows scientists to avoid using the scientific method.

mariabran12

Introduction. Telescope time is a valuablecommodity in astronomy, so astronomers plan their observationscarefully. One of the first steps is to choose what type ofobservation to make. Recall that three basic types of astronomicalobservation are imaging (taking a photograph of anobject), spectroscopy (spreading an object's light into aspectrum), and timing (measuring how an object's lightvaries with time).

Part A: Sort each of the astronomical questionsbelow into the appropriate bin based on the type of observation youwould need to perform to answer it.

Three Categories: Imagine, Spectroscopy andTiming

The Questions:

1. "What are the major surface features of Mars?"

2. "What is the temperature of Jupiter's atmosphere?"

3. "Does the star Mira vary in brightness?"

4. "How large is the Andromeda Galaxy?"

5. "What is the chemical composition of the Crab Nebula?"

6. "Is the X-ray emission fro the galactic center steady orchanging?"

7. "Is the star Vega moving toward us or away from us?"

8. "Are stars in the Orion Nebula surrounded by dusty disks ofgas?"

------------------------

Introduction: Different telescopes areoptimized for observing different wavelengths of light, so anotherconsideration in planning an observation is deciding what type oftelescope to use.

Part B: Each of the following statementsdescribes an astronomical measurement. Place each measurement intothe appropriate bin based on the type of telescope you would use tomake it.

Three Categories: Infrared Telescope, VisibleLight Telescope and X-Ray Telescope

The Statements:

1. Study a dense cloud of cold gas in space.

2. Measure the brightness of a star that is similar to ourSun.

3. Observe the hot (1-million K) gas in the Sun's corona.

4. Obtain a spectrum of sunlight reflected by Mars.

5. Determine the surface temperature of Venus.

6. Look for high-energy radiation from a supernova.

Thank you so much to whoever helps!

To practice Problem-Solving Strategy 21.1 Conservation of energy incharge interactions.

An alpha particle (), which is the same as a helium-4 nucleus, ismomentarily at rest in a region of space occupied by an electricfield. The particle then begins to move. Find the speed of thealpha particle after it has moved through a potential difference of-3.45Ã10-3 .
The charge and the mass of an alpha particle are = 3.20Ã10-19 and =6.68Ã10-27 , respectively.

PROBLEM-SOLVING STRATEGY Conservation of energy in chargeinteractions

PREPARE Draw a before-and-after visual overview. Define symbolsthat will be used in the problem, list known values, and identifywhat you're trying to find.

SOLVE The mathematical representation is based on the law ofconservation of mechanical energy:

.

Find the electric potential at both the initial and finalpositions. You may need to calculate it from a known expression forthe potential, such as that of a point charge.
and are the total kinetic energies of all moving particles.
Some problems may need additional conservation laws, such asconservation of charge or conservation of momentum.
ASSESS Check that your result has the correct units, is reasonable,and answers the question.

Prepare
Identify the system involving the alpha particle. Then examine theforces acting within this system to determine whether mechanicalenergy is conserved. Make certain to draw a before-and-after visualoverview and to define your symbols.
Part A
Mechanical energy is conserved in the presence of which of thefollowing types of forces?
Select all that apply.
? frictional
? electrostatic
? magnetic
? gravitational

Which of the following quantities are unknown?
? the value of the electric potential at the initial position ofthe alpha particle
? the final speed of the alpha particle
? the charge of the alpha particle
? the mass of the alpha particle
? the difference in potential between the initial and finalpositions of the alpha particle
? the value of the electric potential at the final position of thealpha particle
? the initial speed of the alpha particle

HPS250H1 Lecture : 6th Feb 2012.doc

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