Quite incorrect. The inertia does not cause Ali’s glasses suddenly slid toward the opposite direction (left) of car's heading direction (right), as if there was a hidden repulsive force. That's an ILLUSION!

While the car moves in the circular arc at the roundabout, it is in uniform circular motion; that is, it has an acceleration that is directed toward the center of the roundabout. By Newton’s 2nd law, a force must cause this acceleration. Moreover, the force must also be directed toward the center of the roundabout. Thus, it is a centripetal force, which means center-seeking force, where the adjective indicates the direction. The centripetal force, in this case, is provided by the friction between the road and the car’s tires.

Because Ali drove the car, naturally, we assume that he strapped the seat belt on his car’s seat that held him firmly in the seat. This assumption is critical or else, Ali will slide across the seat toward the left and then jam against the car wall for the rest of the turn. Since Ali was wearing his glasses when he turned right, rounding the roundabout, and if his glasses was to move in uniform circular motion along with the car, there must also be a centripetal force on his glasses.

However, apparently the frictional forces on Ali’s glasses from his nose-bridge and ears were not great enough to make his glasses go in a circle with the car. The dirt and oil on Ali’s face could have affected the frictional force. Thus, Ali’s “face” slid beneath his glasses, until he pushes it up with his forefinger so that the frames sit rightly on the top of his nose. Then, the push that Ali provided the needed centripetal force on the glasses allows his glasses to join the car’s uniform circular motion.

If Ali does not attempt to prevent his glass from sliding to his left as he turns right, however, there won’t be a centripetal force acting on his glasses, which would slide off in the direction that is tangent to the circle due to it inertia (according to Newton’s 1st law). This gives Ali the sensation of his glasses slid toward his left. In fact, to a stationary observer, Ali’s glasses are sliding off in a straight line until it jams up against the left wall of the car. The centripetal force from the car wall is required to push the glasses inward along the car’s uniform circular path.



This post has been edited by Critical_Fallacy: Jul 25 2014, 04:51 AM

As stated by maximR, a centripetal force is NOT a new kind of force. The name merely indicates the direction of the force. It's an adjective!! Therefore, it can be a frictional force, a gravitational force, the force from a car wall, the tension force from a string, or any other force in this universe you could name it.



Artificial satellites are continually accelerating towards the Earth. This is because of the gravitational force of attraction between the satellite and the Earth. If a satellite stopped moving forwards, the Earth’s gravitational pull would make it fall to Earth.

This post has been edited by Critical_Fallacy: Jul 25 2014, 04:25 AM

I'm “busy-body” as usual.

Recently I'm expanding my collection of books. A peculiar bibliophile, huh?.

I noticed that your Physics of Motion is now at a whole new level after entering Sunway.

You were talking about “modeling”, a process that most scientists and engineers employ to represent and study a particular real-world system or phenomenon, when many Pre-U students are probably still struggling to understand its concept.

Keep up the good work!

I'm wondering, what do they tell you about centripetal force in your Physics textbook?

In reality, this is a Projectile motion. If you ignore air resistance and resolve the motion of the ball into vertical and horizontal components, you will see that the norm of the horizontal velocity vector stays the same, because the tension from the string is no longer acting on the ball (Newton's 1st Law). The varying vertical velocity vector shows the motion of the ball during its free fall and this is due to gravity acts on the ball (Newton's 2nd Law).

I recall that I shared a link with you on how to get the free & good quality, “OpenStax College Physics” textbook (Web / PDF / EPUB) in this post 3 months ago.

You can also get nearly a dozen of Higher Education textbooks. Just click the image. Choose a high-quality text now!

Most college textbooks on Science and Mathematics are usually very thick. Some authors split the subject in 2 or 3 volumes.

If you really like the book, you should find a printing service center to print out the book in Black & White (or colors) with hardcover binding.

For 1,000++ pages, you can probably negotiate the price.

This is free stuff with bloods & sweats from the Authors. So, don't ridicule!

Physics for Scientists and Engineers with Modern Physics by Serway & Jewett is my primary college physics reference book.



Here is a sample chapter :: Motion in Two Dimensions

Do you mind putting up the Math T assignment on this thread?

Try something else.

Your friend is sure stingy. Gave you formula but no explanation. Anyhow, look at my approach careful. The final formula in the outcome, I've eliminated the Σ sign from the general formula and it is replaced with a more efficient formula.

Part 1 ::


Part 2 ::

It is an attempt to model the dynamic behavior of the concentration in a regularly-spaced drug administration system, as a function of time, t. For simplicity, the assignment requires the students to model the concentration as a function of number of dose, n.

We know that a problem facing physicians is the fact that for most drugs, there is a floor concentration, q, below which the drug is ineffective and a ceiling concentration, Q, above which the drug is dangerous. Thus, the physician would like the have the concentration C(t) satisfy



This requirement helps determine the initial dose of a drug and when the next dose should be administered.

Since we are assuming that when the drug is administered, it is diffused so rapidly throughout the bloodstream that, for all practical purposes, it reaches its highest concentration almost instantaneously, and we would see a spike in the concentration of the drug when the new dose is given, as shown in the piecewise functions below:





As you can see below, the two concentrations (graphs) in the body just before and after every dose as functions of number of dose, are in fact the upper-bound and lower-bound envelopes of the exponential decay model. They are finite data, and not continuous graphs, which you must point out clearly in your assignment Q.1(b). It is advised to use dashed-lines instead of solid lines.



This post has been edited by Critical_Fallacy: Aug 3 2014, 06:47 PM

The purpose of Q.2a(i) is to test your understanding and ability to calculate the steady-state concentrations of both the minimum effective level and the safe limit. In fact, there is no significant difference in concentration between and . You should be able to interpret the following graph:



From the function of the upper-bound envelope, we see that the time constant, τ = 0.7213 day. Using this info, we can predict that the concentration Q(t) will reach steady-state at 4τ = 2.8852 days, or about 3 hours before the 4th dose is given. This is consistent with the graph.



For this reason, in Q.2a(ii) and Q.2a(iii), you need to calculate the concentration of the dosage at least up to Q4 or the 4th dose, in order to determine the drug effectiveness of 50 mg daily dosage on a 35-kg person and a 60-kg person. If you want to, you can also calculate the time interval of ineffectiveness for a specific person before the 2nd dose is given, and justify whether this ineffective time window is acceptable or not.

For example, the minimum effective level for a 35-kg person is 14 mg. And it takes roughly 22 hours from the initial dose 50 mg for the concentration to drop below 14 mg. Say if the 35-kg patient is given IV drip every morning 9:00 a.m., then the ineffective time window is between 7:00 a.m. (14.0 mg) to 9:00 a.m. (12.5 mg) or 2 hours before the 2nd dose is given. Is this acceptable from the physician's view?

This post has been edited by Critical_Fallacy: Aug 4 2014, 06:32 AM

SAMPLE ::
*********

Is your weight truly 50 kg? We are looking at this range of dosage:



Using the formula of sum to infinity, you can calculate the upper range (safe level) of the initial dose based on your body weight.



Similarly, from the derived formula of the concentration just before the 2nd dose, you can calculate the lower range (effective level) of the initial dose based on your body weight.



However, there is a conflict because the value of the lower range cannot be higher than the value of the upper range. Because the safe limit is of higher priority, we need to determine the concentration just before the 3rd dose:



Thus, the effective and safe dosage for every 24 hours should be at this range:

Most Introductory Chemistry textbooks cover more or less the same general materials. They usually differ in the way the authors organize the materials to help students developing a solid understanding and good command of the fundamentals of molecular chemistry. Search for this book in your library. Please inform maximR as well. Because Chemistry and Physics are the two major branches of science that study matter, many physicists also acquire a good command of general chemistry.

Chemistry: A Molecular Approach, 3/e (2014) by Nivaldo J. Tro

1. Background
2. The Problem
3. The Proposed Solution

The ordinary way of writing a typical Introduction:

1. Background
Malaria is caused by a parasite called Plasmodium, which is transmitted via the bites of infected female Anopheles mosquitoes. In the human body, the parasites multiply in the liver, and then infect red blood cells.

2. The Problem
Symptoms of malaria include fever, headache, and vomiting, and usually appear between 10 and 15 days after the mosquito bite. If not treated, malaria can quickly become life-threatening by disrupting the blood supply to vital organs. In 2010, an estimated 219 million cases of malaria occurred worldwide and 660,000 people died, most (91%) in the African Region.

3. The Proposed Solution
Key interventions to control malaria include: prompt and effective treatment with artemisinin-based combination therapies; use of insecticidal nets by people at risk; and indoor residual spraying with insecticide to control the vector mosquitoes.

Treatment of malaria depends on many factors including disease severity, the species of malaria parasite causing the infection and the part of the world in which the infection was acquired. The latter 2 characteristics help determine the probability that the organism is resistant to certain antimalarial drugs. Additional factors such as age, weight, and pregnancy status may limit the available options for malaria treatment.



The Harry Potter way of writing an interesting Introduction:

“It was nearing midnight and I could have written a wonderful Introduction tonight, but I was tired. Not because of bad dreams or pressure at work. No, I was sleepy because of a small winged, creature who snuck into my room and proceeded to offer a high pitched tone directly into my ear. When I turned on the lights to find it, it was not there. When I gave up and attempted sleep, buzzzz… or maybe zzzzinnng? I would find the perfect word, but as mentioned, I am too tired.”

Many people have had this annoying experience with mosquitoes. In fact, according to Animal Planet's The Most Extreme, Season 3, #36: The animals with the highest human kill counts, Mosquitoes are actually the most dangerous animals in the world, killing more than two million people per year. Malaria or a disease resembling malaria has been noted for more than 4,000 years. From the Italian for “bad air,” mal’aria has probably influenced to a great extent human populations and human history.

On August 20th, 1897, Ronald Ross, a British officer in the Indian Medical Service, was the first to demonstrate that malaria parasites could be transmitted from infected patients to mosquitoes. In further work with bird malaria, Ross showed that mosquitoes could transmit malaria parasites from bird to bird. Thus, the problem of malaria transmission was solved. For his discovery, Ross was awarded the Nobel Prize in 1902. (you carry on...)

Methodology is commonly viewed as a combination of general principles and specialized techniques.

What kind of principles and techniques normally used by the ordinary people and the professionals?

Remember that the most important instrument in problem-solving must always be the mind of man.

I thought I can explain that using Physics!

Put a metal spoon into the freezer for 30 min.