A passenger compartment of a rotating amusement park ride contains a bench on which a book
of mass mb is placed, as indicated by the dot in the left figure above. The compartment moves
with a constant angular speed about the center of the ride along a circular path or radius R. The
bench remains horizontal throughout the compartment’s motion. The right figure above shows a
magnified view of the compartment.
The graph below shows the horizontal (x) component of the book’s position as a function of
time, where the +x direction is to the right.

(a) Explain briefly how the graph could be used to determine the period of revolution of the
book.
(b) Can the tangential speed (not the angular speed) be determined from the information given?
Briefly explain why or why not.
(c) What forces act on the book at the lowest point of its circular path? Indicate in words both
the direction and the source of each force.
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Question 1 continued
At the lowest point of the circular path, the book is moving only in the horizontal direction.
Three students are discussing the force of friction on the book. Here are their arguments:
Student 1: At the instant the box is at its lowest position, the book experiences no force of
friction at all, because the net force is only in the vertical direction.
Student 2: At the instant the box is at its lowest position, the book experiences a force of
kinetic friction, because the book and the bench are moving to the right.
Student 3: At the instant the box is at its lowest position, the book experiences a force of
static friction, because the book doesn’t slip relative to the bench.
(d) What is one aspect of student 2’s reasoning that is incorrect? Explain why.
(e) Who is correct, student 1 or student 3? Explain why.
(f) At the lowest point of the circular path, the book is moving only in the horizontal direction.
In what direction, if any, is the net vertical force on the book? Briefly explain your reasoning
in terms of the book’s motion without deriving any equations.

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Question 1 continued
(g) A student is asked to derive an equation for the vertical force Fb that the bench exerts on the
book at the lowest point of the circular path in terms of the book’s mass mb, tangential speed
vb, radius R of the path, and physical constants. Here is the student’s INCORRECT
derivation:

Briefly explain one way in which this student’s derivation is incorrect, and why it is
incorrect.
(h) At the lowest point of the circular path, is the force that the bench exerts on the book greater
than, less than, or equal to the weight of the book? Briefly explain how your answers in (e)
and/or (f) support your choice.
(i) Consider the position of the compartment at the top of the path, and at the bottom of the path.
At which of these positions, if either, is the total mechanical energy of the book greater?
Justify your answer. In your justification, either explain the source of the work done on the
book which changes its mechanical energy, or explain why the book’s mechanical energy did
not change.

a) 120 s

b) v = 0.052R [m/s]

Explanation:

a)

The period of a revolution in a simple harmonic motion is the time taken for the object in motion to complete one cycle (in this case, the time taken to complete one revolution).

The graph of the problem is missing, find it in attachment.

To find the period of revolution of the book, we have to find the time between two consecutive points of the graph that have exactly the same shape, which correspond to two points in which the book is located at the same position.

The first point we take is t = 0, when the position of the book is x = 0.

Then, the next point with same shape is at t = 120 s, where the book returns at x = 0 m.

Therefore, the period is

T = 120 s - 0 s = 120 s

b)

The tangential speed of the book is given by the ratio between the distance covered during one revolution, which is the perimeter of the wheel, and the time taken, which is the period.

The perimeter of the wheel is:

where R is the radius of the wheel.

The period of revolution is:

Therefore, the tangential speed of the book is:

the answer is below

Explanation: The independent variable is the experimental factor which is manipulated and the variable whose effects are being studied. The dependent variable is a variable that could change due to the independent variable. The independent variable is the different ways that Jennifer treats her puppies in order to bring them closer to what she wants in the agility competition. The dependent variable is how they puppies perform each day.

Behavioral shaping is a conditioning procedure where the reinforcers guide behavior toward closer and closer approximations of a desired behavior. Jennifer guided Sasha closer and closer to completing a behavior correctly, thus utilizing shaping in order to bring the puppy closer to what she wanted.

Answer Part A:

1. There is a significant negative relationship between anxiety and academic performance, described as:

a. Subjects with lower anxiety scores have higher current GPAs, or;

b. Subjects who have lower current GPAs have higher anxiety scores.

Explanation:

We can tell that the two variables (anxiety and academic performance) have a negative relationship from its correlation coefficient (-.64). The negative sign shows the relationship, while the statistical significance (p < .01 or p < .05) shows whether there is a relationship or not.

Remember, the power of the correlation (as represented by the number 0.64) does not tell you whether a relationship actually happens or not. It can, however tell the strength of a relationship. A .64 is usually described as moderate to strong, depending on which reference you are using.

Also remember that this is not causation - we do not know which variable causes changes at the other. This is why it is possible to describe the relationship with either option (A) or (B). It is preferable to use a neutral sounding one such as the one stated above: By only saying that there is a negative relationship between the two variables.  

2. There is no relationship between hours sleeping per night and academic performance.

Explanation:

A correlation coefficient of 0.00 means that there is no relationship between two variables. The closer a correlation coefficient to 0, the less likely do the variables have a relationship with one another.

Answer Part B:

1. It contributes to the interpretation of the findings by discussing whether:

(1) The measurement used is appropriate for the research conducted,

(2) There are any limitations from the current method of measurement.

Explanation:

The operational definitions in the study are not explicitly stated, but we can come to our own conclusions from the description of the study. They are:

Academic performance is the current GPA as reported by the research subjects.

Anxiety is the anxiety score summed from the research subjects' responses to the anxiety scale.

Interpretation is usually done during the discussion part of a research journal, after the statistical results have been reported. Discussing operational definitions would help determine whether the right measurement is used. Is the method free of biases? For example, Dr. Aguilera used a 5-point scale to measure the student's anxiety levels; there is a possibility of central tendency bias occurring.

2. Cohort effects may contribute to a possible bias over the result of the research. The variations in both anxiety levels and GPA may not be due to each other's influences, but perhaps instead caused by other age-related experience variables such as social media use.

Explanation:

Cohort effects are defined as a condition shared with same-aged groups of people which affected the result of the research. It is a form of bias, when it is not controlled. Dr. Aguilera's study is at risk of being affected with this since her research subjects are all university students.

In the study, we saw that Dr. Aguilera measured social media use, however, she did not seem to control this variable. It is possible that the variation in anxiety is moderated by social media, which then affects the subjects' GPA.

Something that is persistent remains over time; this is a key characteristic of DDT, which also happens to be a pollutant/pesticide. DDT is able to persist in an environment (as a pollutant) in part due to a phenomenon known as biological magnification. In simpler terms. once DDT enters an ecosystem/trophic structure, it gets worse as you go up the trophic levels; in other words, this means that the worst effects/concentrations of the pesticide will be felt in the uppermost trophic levels (your consumers rather than producers).

The basis for this, however, lies in the fact that organisms of a trophic structure/ecosystem consume each other; they feed on each other to survive (e.g. consumers feeding on producers, higher-level consumers feeding on lower-level consumers, etc.). Thus, once DDT gets into an ecosystem, it can only persist and spread in that ecosystem. Hope this helps :)

The proportion of the available motorcycles that Molly can afford is 60%.

The 30th percentile for the motorcycle is $11920

It should be noted that $25,000 is considered an outlier because it is greater than $24792

Since, mean, μ =  $14,000 and standard deviation, σ = $4,000, the standard variable Z or x = $15,000 will be:

Z = (x - μ)/σ

Z = (15000 - 14000)/4000

Z = 0.25

We then check the table and see that it implies that Molly can buy 60% of the available motorcycles.

The 30th percentile for the prices of motorcycles of this type corresponds to a value of Z = -0.52. This will then be:

x = μ + Z*σ

x = 14000 + (-0.52) × 4000

x = $11920

Lastly, the third quartile value when added to 1.5 x IQR will be equal to:

= 16698 + (1.5 × 5396) = $24792

Therefore, $25,000 is considered an outlier because it is greater than $24792

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Yes, the business journal is interpreting the probability correctly, because 3 out of 5 randomly selected Internet users that will use the mobile payment application, means that, 3/5, or 0.6 of probability. That is exactly the probability reported by the business journal.

Explanation:

Probability that Internet users in the United States will use a mobile payment app is 0.60.

The algorithm's runtime has been divided into two main categories are given below.

Explanation:

Then maybe we can easily see by the information collected that perhaps the algorithm is increasing at either the frequency of 20×n. At which, across every iteration, n seems to be the input dimension. This suggests that perhaps the runtime specified seems to be of a polynomial category, therefore means that even this technique executes within a rational period.

To generate objective knowledge about any area it is important to use the scientific method. The scientific method uses measurement, analysis, observation, and experimentation to obtain objective data to validate the hypotheses and generate knowledge.

In this case, City University carried out a scientific investigation to verify that its students were happy throughout the time in the university. For the investigation, they used an instrument that evaluates satisfaction. The results indicate that the senior-students are happier than the first-year students, for that the university officials conclude that the students are happier when they attend university for a longer time. This is convenient to attract new students and not change to another study center.

I hope this information can help you.

B

Explanation: