PHIL 367 Lecture : PHIL 367 - Lecture (Jan. 30th)

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champagnegoat805

30 Jan 2012

School

McGill University

Department

Philosophy

Course

PHIL 367

Professor

Susan Judith Hoffmann

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Document Summary

The i asserts its freedom action, and the i is determined and limited by the objective world (external reality), yet it acts upon that world; it also determines that world, and changes it. This is how the i satisfies its desire and natural impulse to manifest and assert its freedom. But, the i in its endless striving, would only be completely and wholly satisfied in practise in completely overcoming, changing, appropriating objectivity as a whole. Therefore, the i would only achieve satisfaction by becoming the absolute i. Philosophical problem: for the i to be absolute, there would be no consciousness, for there would be nothing left for the i to be conscious of. There would be nothing left of the ego"s absoluteness. In an absolute state, there would no longer be content nor objectivity. The individual finite i"s desire to wholly appropriate objectivity is in some sense the annihilation of reason.

Related Questions

In this problem we will consider a collision of two moving objects such that after the collision, the objects stick together and travel off as a single unit. The collision is therefore completely inelastic.

You have probably learned that "momentum is conserved" in an inelastic collision. But how does this fact help you to solve collision problems? The following questions should help you to clarify the meaning and implications of the statement "momentum is conserved."

1)What physical quantities are conserved in this collision?
a) the magnitude of the momentum only
b) the net momentum (considered as a vector) only
c) the momentum of each object considered individually

2) Two cars of equal mass collide inelastically and stick together after the collision. Before the collision, their speeds are V1 and V2 . What is the speed of the two-car system after the collision?
g)The answer depends on the directions in which the cars were moving before the collision.

3) Two cars collide inelastically and stick together after the collision. Before the collision, the magnitudes of their momenta are P1 and P2. After the collision, what is the magnitude of their combined momentum?

a) P1+P2
b) P1-P2
c) P2-P1
d)(P1P2)^(1/2)
e) (1/2)(P1+P2)
f)(P1+P2)^(1/2)
g)The answer depends on the directions in which the cars were moving before the collision.

4) Two cars collide inelastically and stick together after the collision. Before the collision, their momenta are p1 and p2. After the collision, their combined momentum is vector p. Of what can one be certain?

a) Vector P= p1+p2
b) Vector P= p1-p2
c) Vector P= p2-p1

taupecamel748

Consider three identical spherical conductors. One conductor,labeled A, is given a
charge of 7mC of type Nell. The charge state of the second andthird conductors, B and C, are unknown. The conductors undergo asequence of 3 contacts that occur ONLY between pairs of conductors.After the contacts, the net charge on each conductor is A: (0.25mCof type Nell), B: (1.875mC of type Nell) and C: (1.875mC of typeNell). Letâs make the assumption that the type Paul charge statecorresponds to an excess of electrons.

Because these three spheres are ______________________ the_______________ can be
freely exchanged between any pair of conductors in contact. Sincethese conductive
spheres all have the same size, when the spheres are placed incontact the ______
_____________ will evenly distribute between the two spheres.Because charge is a
property of particles and the particles can not be destroyed ANDthere is no outside
source of charge, the _______________ charge of the ______________must remain
constant at 4mC of type Nell. Based on this information, we candetermine that the
charge of at least one of B or C must be of type_______________.

To determine the order of contacts we must start from the lastcontact and work our way to the first contact. It is important tonote that because we have no initial charge state information forspheres B and C that we have the ability to make an arbitrarydecision about the initial charge state of these two spheres. Inother words, the charge states of sphere B and C areinterchangeable. Third and last Contact: Because spheres ________and _______ have the same charge we can determine that they were______ in contact. If we look at spheres B and C as the system, wefind that the total charge of the sub system consisting of B and Cwas ______________ of type _________.

Second contact: We can safely assume that A touched either B or Cprior to B and C
being brought into contact. Here we can make the arbitrary choicethat B touched A in the second contact. If this is the case, weknow that the charge of B ___________ it touched C must have been______________ of type __________ because it must have the sameamount and type of charge as the final state of _______. Therefore,at this instant we know that the charge on sphere C was________________ of type ____________________ it touched B.

First contact: Now we have an interesting situation. We find thatthe charge state of
sphere C would be consistent with sphere C being initially____________ and being
placed in contact with _______________ since the charge state of Cis exactly
__________ that of ____________ initially. This would mean that thecharge state of
sphere A after contact with ______ would be _____________ of type__________.
However, we already determined that the __________ charge of thesystem containing sphere _______ and sphere _______ in the secondcontact was ____________ of type __________. The only way this ispossible is if sphere B has a charge of __________ of type____________.

Final Results
The initial charge state of sphere Ais:_________________________________________
The initial charge state of sphere Bis:_________________________________________
The initial charge state of sphere Cis:_________________________________________
In the first contact of sphere ___________ to sphere_________________ how many
electrons were transferred from one sphere to the other?
In the second contact of sphere ___________ to sphere_________________ how many
electrons were transferred from one sphere to the other?
In the third contact of sphere ___________ to sphere_________________ how many
electrons were transferred from one sphere to the other?

Huygens' principle (first described by the Dutch scientist Christiaan Huygens in 1678) uses geometry to determine the shape of a wavefront at a time t, given some initial wavefront at an earlier time. This can be constructed by imagining that the initial wavefront is a source of wavelets that propagate from each point at the speed of light. From this principle, one can determine the angles of reflection and refraction by considering the speed of light at each point on the wavefront. In this problem, we will explore some of these concepts.

Part A

First, let's look at a plane wave that is incident on a flat piece of material with an index of refraction n. Part of the light is transmitted through the material and part of it is reflected. For the moment, let's just look at the part that is transmitted. At time t=0, the wavefront is a distance d away from the surface of the material. At time t=t₁, the wavefront is at the position of the material interface. Use the Huygens' principle to determine how far into the material (d') the wavefront has propagated by time t=2t₁.

Express your answer in terms of the variables n, t₁, and the speed of light in a vacuum c.

Note that there would be no change in the direction of the wavefront at any point because the wavefront encountered the material interface at the same time at all points. Thus, all of the individual wavefronts all propagated at the same speed, thereby maintaining the flat wavefront.

Now, instead of having a flat wavefront propagating normal to the material interface, we have a flat wavefront propagating toward the material at an angle of 55° to the axis perpendicular to the material interface. In this part, we will look at the relative positions of a few points—A, B, and C—on the wavefront to illustrate Huygens' principle. (Intro 1 figure) Point C touches the vacuum/material interface at time t=0 whereas point B is a distance d and point A is a distance 2d away from the interface.

Part B

What is the time t_B it will take for point B of the wavefront to encounter the vacuum/material interface?

Express your answer numerically to two decimal places in units of t₁ (the time it takes light to travel a distance d in a vacuum).

It should be noted that the accuracy of the method increases the smaller the distance is before making a new wavefront and redoing the wavelets. If you tried to just draw a large wavelet from point B, then it would hit the surface after only traveling a distance d. This large wavelet would make it difficult to visualize how to add up all of the other wavelets to make a coherent wavefront. As a result, one should just draw a line perpendicular to the wavefront at point B until it hits the surface, at which point the wavelets will change owing to the new index of refraction.

Part C

How far did point C go into the material interface in the time t=t_B that it took for point B to get to the interface? For this part we are looking for the distance traversed by the point C in the material (d_C).

Give your answer in terms of the time t_B, c, and n.

Part D

What is the new angle θ at which point C of the wavefront is propagating (relative to a line perpendicular to the vacuum/material interface)? Try to use the fact that you have a spherical wavefront propagating from t=0 at the point where C met the vacuum/material interface until time t_B when the wavefront at point B reached the interface.

Express your answer in terms of inverse trigonometric functions and n.

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PHIL 367 Lecture : PHIL 367 - Lecture (Jan. 30th)

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