PHL271H1 Lecture Notes - Blackboard

31 views5 pages

erinmole26

17 Jun 2011

School

Department

Course

Professor

For unlimited access to Class Notes, a Class+ subscription is required.

Document Summary

Positivism wasn"t being taken seriously so hart wanted to reestablish it. Distinguish from command theory & responding to other criticisms. Positivism draws a crucial distinction between law and morals. It separates the question is this a law? from the question is this moral/just? . passed by an authority (such as legislature, judicial decisions) sanctions attached to some of them for disobedience. influence out behaviour/provide guidance (through general acceptance, also through our own reason) *even if it"s not necessarily just or moral (p. g. A rule can violate standards of morality but still be law. Conversely, just b/c a rule is moral that doesn"t make it a rule of law. It doesn"t make the assertion that law and morality are separate there are certain cases in which positivism accepts the intersection between laws and morals. Sense of it being publicly acceptable to be discriminatory partially b/c of laws. In these ways laws and morals connect (historical connection)

Related Questions

Figure 21-29(a) shows an arrangement of three charged particles.Particles A and C are fixed on the x axis, but particle B can bemoved along a circle centered on particle A. During the movement, aradial line between A and B makes an angle Î¸ relative to thepositive direction of the x axis (figure 21-29(b)). The curves infigure (c) below give, for two situations, the magnitude Fnet ofthe net electrostatic force on particle A due to the otherparticles. That net force is given as a function of angle Î¸ and asa multiple of a basic amount F0. For example on curve 1, at Î¸ =180o, we see that Fnet = 2F0. (a) For the situation correspondingto curve 1, what is the ratio of the charge of particle C to thatof particle B (including sign)? (b) For the situation correspondingto curve 2, what is that ratio?

Part A Curve 1: In the solution provided to this question F0=force of particle B on particle A and F is the force of particle Con particle A. We are given that Fnet=2F0 at Î¸=180*

How do we know that 2F₀= F₀-F? (Doesn't this meanthat F0=2Fo+F which doesn't make sense?)

Part B Curve 2: it is clear that the ratio ofF_max/F_min = 1.25/0.75 What comes after that..the solution says:

5/3= (1+(1/4) q_A/q_C) / (1-(1/4)q_A/q_C)

what is the next step to simplify this and get a solution..?

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.

goldpug777

Good Vibes: Introduction to Oscillations

The conditions that lead to simple harmonic motion are as follows:

There must be a position of stable equilibrium.

There must be a restoring force acting on the oscillating object. The direction of this force must always point toward the equilibrium, and its magnitude must be directly proportional to the magnitude of the object's displacement from its equilibrium position. Mathematically, the restoring force F⃗ is given by ⃗, where is the displacement from equilibrium and k is a constant that depends on the properties of the oscillating system.

The resistive forces in the system must be reasonably small.

Consider a block of mass m attached to a spring with force constant k, as shown in the figure(Figure 1) . The spring can be either stretched or compressed. The block slides on a frictionless horizontal surface, as shown. When the spring is relaxed, the block is located at x=0. If the block is pulled to the right a distance A and then released, A will be the amplitude of the resulting oscillations.

Assume that the mechanical energy of the block-spring system remains unchanged in the subsequent motion of the block.

Part A

After the block is released from x=A, it will

(a) remain at rest

(b) move to the left until it reaches equilibrium and stop there.

(d) move to the left until it reaches x=−A and then begin to move to the right.

The time it takes the block to complete one cycle is called the period. Usually, the period is denoted T and is measured in seconds.

The frequency, denoted f, is the number of cycles that are completed per unit of time: f=1/T. In SI units, f is measured in inverse seconds, or hertz (Hz).

Part B

If the period is doubled, the frequency is

(a) unchanged

(b) doubled

Part C

An oscillating object takes 0.10 s to complete one cycle; that is, its period is 0.10 s. What is its frequency f?

Express your answer in hertz.

Part D

If the frequency is 40 Hz, what is the period T?

Express your answer in seconds.

The following questions refer to the figure (Figure 2) that graphically depicts the oscillations of the block on the spring.

Note that the vertical axis represents the x-coordinate of the oscillating object, and the horizontal axis represents time.

Part E

Which points on the x-axis are located at a distance A from the equilibrium position?

(a) R only

(b) Q only

Part F

Suppose that the period is T. Which of the following points on the t-axis are separated by the time interval T?

(a) K and L

(b) K and M

(d) L and N

(e) M and P

Now assume for the remaining Parts G - J, that the x coordinate of point R is 0.12 m and the t coordinate of point K is 0.0050 s.

Part G

What is the period T?

Express your answer in seconds.

Part H

How much time t does the block take to travel from the point of maximum displacement to the opposite point of maximum displacement?

Express your answer in seconds.

Part I

What distance d does the object cover during one period of oscillation?

Express your answer in meters.

Part J

What distance d does the object cover between the moments labeled K and N on the graph?

Express your answer in meters.

emeraldyak680

PHL271H1 Lecture Notes - Blackboard

Document Summary

Get access

Related Documents

PHL271H1 Lecture Notes - Lecture 1: Legal Positivism

PHL271H1 Lecture Notes - Lecture 2: Jim Crow Laws, Golden Rule, Thought Experiment

PHL271H1 Lecture Notes - Lecture 2: Legal Positivism

Related Questions