PHIL 100W Lecture : phil 100 lec 13

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12 Feb 2012

School

Simon Fraser University

Department

Philosophy

Course

PHIL 100W

Professor

Peter Horban

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Document Summary

If materialism is true, then happenings in the neural machinery of the brain provide a necessary and sufficient explanation of the totality both of the performance and of the conscious experience of a human being. Thus, purely physical conditions, conditions within the brain, cause us to say or to believe whatever we say or believe. On this view, then, the real reason why some people think that materialism is true is that certain atoms are arranged a particular way inside their skulls. Let"s suppose that physicalism and evolutionary theory are both correct (that is, let"s suppose that the thesis of naturalistic evolution is true). One might be inclined to give an account framed in terms of survival value. However, true beliefs as such don"t have survival value. What evolution requires is that our behavior have survival value, not necessarily that our beliefs be true.

Related Questions

A centrifuge is a device in which a small container of materialisrotated at a high speed on a circular path. Such a device isusedin medical laboratories, for instance, to cause the more denseredblood cells to settle through the less dense blood serumandcollect at the bottom of the container. Suppose thecentripetalacceleration of the sample is 3.08 x 10³times as largeas the acceleration due to gravity. How manyrevolutions per minuteis the sample making, if it is located at aradius of 2.72 cm fromthe axis of rotation?

How fast can a racecar travel through a circular tum without skidding and hitting the wall? The answer could depend on several factors:

The weight of the car;
The friction between the tires and the road;
The radius of the circle;
The “steepness” of the turn.

In this project, we investigate this question for NASCAR racecars at the Bristol Motor Speedway in Tennessee. Before considering this track in particular, we use vector functions to develop the mathematics and physics necessary for answering questions such as this.

A car of mass m moves with constant angular speed to around a circular curve of radius R (Figure 3.20). The curve is banked at an angle . If the height of the car off the ground is h, then the position of the car at time t is given by the function

As the car moves around the curve, three forces act on it: gravity, the force exerted by the road (this force is perpendicular to the ground), and the friction force (Figure 3.21). Because describing the frictional force generated by the tires and the road is complex, we use a standard approximation for the frictional force. Assume that for some positive constant . The constant is called the coefficient of friction.

Let denote the maximum speed the car can attain through the curve without skidding. In other words, is the fastest speed at which the car can navigate the turn. When the car is navigate at this speed, the magnitude of the centripetal force is

The next three questions deal with developing a formula that relates the speed to the banking angle .

Now that we have a formula relating the maximum speed of the car and the banking angle, we are in a position to answer the questions like the one posed at the beginning of the project.

The Bristol Motor Speedway is a NASCAR short track in Bristol, Tennessee. The track has the approximate shape shown in Figure 3.22. Each end of the track is approximately semicircular, so when cars make turns they are traveling along an approximately circular curve. If a car takes the inside track and speeds along the bottom of turn 1, the car travels along a semicircle of radius approximately with a banking angle of . If the car decides to take the outside track and speeds along the top of turn 1, then the car travels along a semicircle with a banking angle of . (The track has variable angle banking.)

The coefficient of friction for a normal fire in Elly conditions is approximately . Therefore, we assume the coefficient for a NASCAR tire in dry conditions is approximately .

Before answering the following questions, note that it is easier to do computations in terms of feet and seconds, and then convert the answers to miles per hour as a final step.

11. Suppose the measured speed of a car going along the outside edge of the turn is . Estimate the coefficient of friction for the car’s tires.

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Suppose we have reason to suspect that a certain quantum objecthasonly three quantum states. When we excite a collection ofsuchobjects we observe that they emit electromagnetic radiationofthree different energies: 0.9 eV (infrared), 1.9 eV (visible),and 2.8 eV (visible).

(a) Draw a possible energy-level diagram for one of thequantumobjects, which has three bound states. On the diagram,indicate thetransitions corresponding to the emitted photons, andcheck thatthe possible transitions produce the observed photons andnoothers. When you are sure that your energy-level diagramisconsistent with the observed photon energies, enter the energiesofeach level (K+U, which is negative). EnterALLlevels before submitting; all of the energies must be correctto beproperly scored. The energy K+U of theground state is -4eV.