A Hall-effect probe operates with a 121 mA current. When the probe is placed in a uniform magnetic field with a magnitude of 0.0758 T, it produces a Hall voltage of 0.691 µV. When it is measuring an unknown magnetic field, the Hall voltage is 0.337 µV. What is the unknown magnitude of the field? B.If the thickness of the probe in the direction of B is 1.88 mm, calculate the charge-carrier density (each of charge e).?

Shells aren’t the only thing that make-up limestones- skeletal fragments from coral and forams, among other things. However these all consist of calcium carbonate (CaCO3), which reacts and is soluble to even weak acids. Given that rainwater is slightly acidic, use this information to explain why Florida, which primarily consists of limestone bedrock, has so many sink-holes.

To give a 18-{rm kg} child a ride, two teenagers pull on a 3.6-{rm kg} sled with ropes, as indicated in the figure . Both teenagers pull with a force of 55 {rm N} at an angle of 35 ^circ relative to the forward direction, which is the direction of motion. In addition, the snow exerts a retarding force on the sled that points opposite to the direction of motion, and has a magnitude of 57 {rm N}.Find the acceleration of the sled and child.

Reply posts 100-200 words

#1

For this forum post I chose an article titled “Hurricanes and Climate Change”, published by an organization called Union of Concerned Scientists. I chose this because the topic of this article is relevant to my research topic. In addition to this I researched key aspects and points of consideration when attempting to determine the credibility.  I took some of these key points and applied them to my selected article.

Firstly I considered the source of the article. While the “Union of Concerned Scientist” sounds professional, it lacks any affiliation to established academic entities. While the organization’s membership includes professional scientist it is predominantly an advocacy group. This brought me to another determining factor of source and article credibility, bias. With the publisher being above all an advocacy group, their objectivity must be considered.  As an advocacy group there is a strong possibility that an agenda competes with objectivity in the publishing of articles. Another small but significant aspect I noticed with this article is the lack of an accredited author. The absence of an author not only detracts from the credibility of the article but from the organization that allows it to be published as well. A highly credible organization would almost certainly require published material to posses an author acknowledgment.

The one aspect of credibility evaluation that the article passes with flying colors is the advertisements present on their page or more appropriately the lack there of. The format of the website seem professional and of an academic nature. Cheap advertisements and tabloid material are noticeably absent. Credible institutions are not as beholden to advertisement money.

In my personal opinion my selected article is a shade of grey when it comes to credibility. I feel that there is factual information within this article however the established possibility of a bias or agenda puts everything into question. The presentation of the website has all the benchmarks of a credibility, minus the anonymous author, however the publishing organization lacks a firm grounding in research or academia. Ultimately I would not feel comfortable using this article as a source. 

References:

• Rogers, T. (2019, January 24). 8 Ways to Determine Website Reliability. Retrieved February 11, 2019, from https://www.thoughtco.com/gauging-website-reliability-2073838
• Hurricanes and Climate Change. (2017, December 01). Retrieved February 11, 2019, from https://www.ucsusa.org/global-warming/science-and-impacts/impacts/hurricanes-and-climate-change.html#.XGHLRS2ZMrU

#2

For this week post, I have chosen a source that can easily be found with a simple web search. In fact, it took me less than 5 minutes to find the source.  This is directly related to my final project on Hurricane Katrina. In this post, I will describe the source, go over how I located it and conduct an evaluation of it.  The title of my source is “Tropical Cyclone Report Hurricane Katrina,” from the National Hurricane Center (Knabb, 2005).

I would describe this as scholarly government information.  It is pretty clear the authors produce a paper with high scholarly standards and being that is a paper published by the National Hurricane Center (part of the National Oceanic and Atmospheric Administration, or NOAA) it is government information.  It is 43 pages long and divided into two parts: 1) written report and 2) tables/figures.

The way I conduct my search for this source can be explained in 5 steps:

Step One: Use a web-based search engine. I used Google and use “NOAA Hurricane” as my search term. I choose this search term, I knew that NOAA is the US government agency responsible for weather data collection. I added “hurricane” to the term, because the subject of my final project is Hurricane Katrina.

Step Two: Select from search results: I selected the link for the National Hurricane Center because I believe it would provide the best information on my final project topic.

Step Three: Search the website: I saw that there was a search bar on the header bar for the website home page. I choose “Katrina” as my search term.

Step Four: Select for search results: I selected the paper entitled “Tropical Cyclone Report Hurricane Katrina (Knabb, 2005),” because it looked to be related to my final project topic.

Step Five: Evaluate the source:  When evaluating the paper, I choose the following criteria: authority, accuracy, objectivity, depth, and relevance.

Authority: The paper is produced by the US Government’s office which focuses on the hurricane, which means it rates high in this criterion.

Accuracy: The paper is full of measurement data, as well as statistics on the hurricane’s impact on the affected areas. It cites all of its sources, which means it rates high in this criterion.

Objectivity: As stated above this is a product of the US Government. It is clear the paper attempt to be objective. In the written report there is a subsection entitled “Forecast and Warning Critique (Knabb, 2005),” which goes over some of the issued identity about the forecasting during Hurricane Katrina. This results in a high rating for this criterion.

Depth: The paper dives deep into the measurement data and statistics, and completely cover the hurricane, start to finish, which mean it rates high in this criterion.

Relevance: The paper sole purpose it the report the event, Hurricane Katrina, and is completely relevant to my final project. It rate high in this criterion.

References

Knabb, R. D. (2005, DEC 20). Tropical Cyclone Report Hurricane Katrina. Retrieved FEB 11, 2019, from National Hurricane Center: https://www.nhc.noaa.gov/data/tcr/AL122005_Katrina.pdf