A fire work rocket is fired vertically upward. At its maximum height of 100.0 m, it explodes and breaks into two pieces, one with mass 1.40 kg and...

Denote the (positive) speeds of objects just after explosion as `V_1` and `V_2` , and their masses as `m_1` and `m_2` . The directions of `V_1` and `V_2` are the opposite.

Then conservation of impulse gives us `m_1 V_1=m_2 V_2,` because the speed just before the explosion was zero. The conservation of energy gives `m_1 V_1^2+m_2 V_2^2=J` (the chemical energy that becomes kinetic).

Solving this system of equations is easy:

`V_1=m_2/m_1 V_2,` substitute it to the second equation and obtain `m_2/m_1 (m_2+m_1) V_2^2=2 J,` so

`V_2^2=2 J m_1/m_2 1/(m_1+m_2)` and `V_1^2=2 J m_2/m_1 1/(m_1+m_2).`

In numbers, they will be equal to

`V_1=sqrt(1800/1.7 0.3/1.4) approx 15(m/s),` `V_2=sqrt(1800/1.7 1.4/0.3) approx 70(m/s).`

For the second part of the question we have to consider an angle between the velocity of the first object and a horizontal line, and write the equations of horizontal and vertical movements of both bodies.

In the novel To Kill a Mockingbird by Harper Lee, why does Miss Maudie say that it is a sin to kill a mockingbird?

In Chapter 10, Scout and Jem are shooting their air rifles and Atticus tells them that they can shoot all the bluejays they want, but it is a sin to kill a mockingbird. Scout mentions that it was the first time she ever heard her father say that it was a sin to do something and decides to ask Miss Maudie about it. Miss Maudie tells Scout that it is a sin to kill a mockingbird because they do nothing except make beautiful music for people to enjoy. She also comments that mockingbirds do not eat up people's gardens or nest in corncribs, and only "sing their hearts out for us" (Lee 119). Mockingbirds are essentially innocent beings that do not deserve to be shot or harmed. Throughout the novel, various characters, like Tom Robinson and Boo Radley, are represented as symbolic "mockingbirds" because they cause no harm to anyone. When Tom Robinson is wrongfully convicted of raping and assaulting Mayella Ewell, it is metaphorically comparable to a person killing a mockingbird. Tom Robinson was an innocent man who was unfairly harmed which demonstrates that Atticus' lesson can apply to respecting any innocent being, and not just mockingbirds.

What does the word "clamoured" likely mean in the sentence "I reapproached the wall; I replied to the yells of him who clamoured" in "The Cask of...

Let's look at what the sentence means. It seems to be saying, "I replied to the yells of the guy who was yelling," or, "I replied to the yells of the guy who was making all that noise."

So, the context reveals that "clamor" (or "clamour," as Poe preferred to spell it) means "to make a loud noise, such as yelling."

In this case, the context lead us to the right conclusion. To clamor does mean to shout or to cry out in a loud way. It can be something that one person does alone, but often it's something that people do in a group, like this: "The kids clamored for ice cream." (It means they're making loud shouts as they ask for ice cream.)

"Clamor" comes from the same Latin root as some other words you already know: "exclaim" and "claim." That explains why "clamor" looks like "claim" and "exclaim," and it makes sense, too: "exclaim," "claim," and "clamor" all involve some sort of shouting out.

"Wait," you might say. "But the word 'clamor' doesn't add any meaning to the sentence from the story. Why didn't Poe just write, 'I replied to the yells'?"

Good question! Have you noticed how Poe loves fancy words, and how he loves to write long, flowing, formal, sometimes-repetitive sentences? It's just in his nature as a writer of horror stories to be a bit redundant at times. Here, Poe was repeating the idea that Fortunato was desperately crying out. Luckily for us, the way Poe uses words in such clear contexts does help us learn those words from his stories, which is great!

As a teenager, what daydream does Dexter Green have about the men he caddies for?

We'll find this answer in the fourth paragraph of the story:

"He became a golf champion and defeated Mr. T. A. Hedrick in a marvellous match played a hundred times over the fairways of his imagination, a match each detail of which he changed about untiringly--sometimes he won with almost laughable ease, sometimes he came up magnificently from behind. Again, stepping from a Pierce-Arrow automobile, like Mr. Mortimer Jones, he strolled frigidly into the lounge of the Sherry Island Golf Club-- or perhaps, surrounded by an admiring crowd, he gave an exhibition of fancy diving from the spring-board of the club raft. . . . Among those who watched him in open-mouthed wonder was Mr. Mortimer Jones."

As you can see, while Dexter is working as a caddy during his teen years, he imagines that he becomes a fantastic golf player himself. He fantasizes about beating Mr. Hedrick (one of the men Dexter caddies for) in lots of different ways: sometimes in a straightforward way, and sometimes in a slower, sneaky, more startling way. In his daydreams of success on the golf course, Dexter also gets out of a fancy car and walks inside the club building (like his boss Mr. Jones does in real life) and sometimes he does a skillful dive into the water while lots of people watch him admiringly.

Basically, Dexter daydreams about not just being one of the men caddies for, but being the most successful of them and the most admired among them.

Dexter's daydreams here indicate that he craves success, power, wealth, and the admiration of others. As the story continues and Dexter grows up, his basic desires don't change, but the specific ways in which he seeks to satisfy them do. For example, as a kid, Dexter wants to be admired as a golf champion. But as a young adult, Dexter wants to "win" Judy for himself; she's the new, grown-up version of a prize or trophy, in Dexter's mind. However, the one thing that stays the same is Dexter's desire for great wealth. He remains ambitious, surprising even himself with the financial success he eventually gains. But it doesn't make him happy.

What are occupational exposures that can lead to cancer?

Related conditions:
Cancers linked to occupational exposure include leukemia, lymphoma, and cancers of the lung, breast, bladder, skin, larynx, nose, throat, prostate, pancreas, liver, scrotum, and soft tissue.

Workers at risk: The International Agency for Research on Cancer (IARC) has identified over one hundred known and about one hundred suspected occupational carcinogens. Certain workplaces and jobs carry a greater risk of exposing workers to substances that may increase their chance of cancer. The workplace may be indoors, as with restaurant or factory workers, or outdoors, as with landscapers or construction workers. Because the effects of exposure to occupational toxins usually do not surface until years after exposure, linking the cancer to the workplace is sometimes difficult. However, one in five workers is exposed to and at an increased risk for cancer from toxins in the workplace.

The World Health Organization (WHO) reported that of the more than seven million deaths from cancer each year, about 40 percent could be prevented by dedicated efforts to reduce workplace toxins. Occupational cancer claims more lives than any other work-related disease (32 percent; circulatory disease claims 26 percent) or even work accidents (17 percent). The incidence of occupational cancers is from 4 to 20 percent of all cancers but may be higher, as many go unreported. In the United States, each year about twenty thousand people die of cancers attributed to occupational toxins and about forty thousand people are newly diagnosed with cancers due to occupational causes. Globally, an estimated 609,000 workers are affected yearly.

Lung cancer:

Lung cancer has been linked to occupational exposure to numerous substances. Lung cancer, particularly mesothelioma, is high in people exposed to asbestos and can develop years after the exposure. If the person exposed to asbestos is a smoker, that person is fifty to ninety times more likely to be diagnosed with lung cancer compared with the average person. Asbestos has been used to strengthen the walls of buildings; as insulation for walls, boiler pipes, and steam pipes; and as soundproofing. In 1989, the United States Environmental Protection Agency (EPA) banned most asbestos-containing products. Although the ruling was overturned in a 1991 appeal, some asbestos-containing products remain prohibited, and all nonhistorical, or new, uses are banned. Therefore, automobile parts manufacturers still use asbestos in brake shoes and clutch linings. Some products contain substances that may be contamined with asbestos, such as vermiculite (in garden products) and talc (in crayons). Asbestos often is present in the ceiling or floor tiles in older buildings. Workers who remove asbestos-containing materials from old buildings need to use protective masks to avoid inhalation and cover their clothes so they do not take asbestos dust home with them. Other industries where employees can be exposed to asbestos are railroads, insulation factories, and shipbuilders.

Lung cancer risk is increased for people who work in places where they are exposed to secondhand smoke, such as bars, casinos, bowling alleys, or restaurants; tin miners and refining industry workers who are exposed to toxins such as arsenic, nickel, or chloromethyl ether; and quarrying, stone industry, and glass-manufacturing workers exposed to silica dust.

Radon, a natural radioactive gas that causes lung cancer, is present at harmful levels in one in fifteen homes by the EPA’s estimate. Chemicals inhaled by painters, chemists, and printers increase their risk of lung cancer. Formaldehyde, a chemical used to disinfect surgical rooms and dialysis units and also found in carpet and furniture glues, diesel fumes, and embalming fluid, is believed to cause respiratory cancers.

Bladder cancer:

Bladder cancer has been linked to exposure to dyes containing benzine and naphthylamine. IARC found a small increased risk of developing bladder cancer among barbers and male hairdressers. However, some cancer-causing coloring agents were removed from dyes in the 1970s, and the study was unable to determine if the risk was caused by past or present exposure to carcinogens. Employees who work with rubber, paint, or leathers may also be at greater risk of developing bladder cancer.

Skin cancer:
Skin cancers such as melanomas are more common in workers who are exposed to the ultraviolet (UV) radiation from the sun. Workers at greater risk include construction workers, farmworkers, landscapers, roofers, and fishing boat workers. Asphalt and diphenyls as well as reflections from water, sand, concrete, snow, and any light-colored surface increase the harmful effects of UV rays.

Other cancers: Workers exposed to herbicides and pesticides have an increased risk of lymphomas. Farmers and others working with these chemicals demonstrate a higher incidence of prostate cancer. Pancreatic cancer is associated with pesticides, dyes, and gasoline. Health care workers can be exposed to occupational toxins as well as body fluids that harbor hepatitis B and C viruses, which can cause liver cancer.

Prevention and policy: Occupational exposures to carcinogens can be limited and in many cases are preventable. Removing the risk or the toxin from the workplace is the primary way to prevent occupational cancer. When the carcinogen cannot be removed from the environment, as in the case of UV rays, workers can use protective clothing and sunscreens, and work practices can be altered to minimize exposure (such as providing a shady place for breaks and lunches). The WHO’s Global Occupational Health Network offers the following steps to prevent occupational cancers:

• Develop regulations and an enforcement process for monitoring carcinogens in the workplace.





• Avoid use of known carcinogens in the workplace.





• Replace known toxins with safe substitutes.





• Educate workers about primary prevention of work-related cancers.





• Implement a health surveillance program for workers exposed to occupational toxins.

Several other approaches can decrease the risk of occupational cancer. These include testing of new chemicals before they are placed on the market, keeping hazardous toxins in an enclosed area with adequate ventilation, and using protective masks and clothing. Workers are advised to avoid smoking, as the incidence of occupational cancer increases with tobacco use. All workers must examine and weigh the risk that each occupation brings, as few jobs are risk-free, but some involve more exposure than others.

The prevention of occupational cancer is directly related to legislation as laws are needed to control the use of carcinogens and to provide workers with adequate protection from exposure. Legislators, politicians, lobbyists, unions, and grassroots occupational health groups have brought pressure on the various industries to introduce protective laws and stricter inspections.

Blanc, Paul D. How Everyday Products Make People Sick: Toxins at Home and in the Workplace. Berkeley: U of California P, 2007. Print.

Bozzone, Donna M. Causes of Cancer. New York: Chelsea House, 2007. Print.

"Environmental and Occupational Cancers." WHO.int. World Health Organization, March 2011. Web. 25 Nov. 2014.

Landrigan, Phillip J. “Prevention of Occupational Cancer.” CA Cancer Journal for Clinicians 46 (1996): 67–69. Print.

"Occupational Cancer." CDC.gov. Centers for Disease Control and Prevention, 2 May 2012. Web. 25 Nov. 2014.

Raffle, P. B., et al., eds. Hunter’s Diseases of Occupations. 8th ed. Boston: Arnold, 1994. Print.

Rapp, Doris J. Our Toxic World: A Wake Up Call. New York: Environmental Medical Research Foundation, 2004. Print.

"Research Day 2011: The Burden of Occupational Cancer." OccupationalCancer.ca. Occupational Cancer Research Centre, 2011. Web. 25 Nov. 2014.

Veys, C. A. “ABC of Work Related Disorders: Occupational Cancer.” British Medical Journal 313 (1996): 615–19. Print.

Was the Great Depression Hoover's fault?

The Great Depression was not President Herbert Hoover's fault. All the factors that led to the Depression were in play when he took the oath of office of the Presidency in 1929. The farming crisis and slowdown in manufacturing that many point to as crucial factors in the onset of the Depression dated back to the mid-twenties, and the blame for the rising consumer debt and structural economic changes that led to the Depression can scarcely be blamed on him. What might be argued, however, is that Hoover failed to take drastic action in response to the Depression. In particular, he declined to engage in direct aid and relief for Americans affected by the economic downturn. While his response was more robust than is commonly believed (or as believed at the time by those who lived in "Hoovervilles"), he certainly did not engage in the kinds of sweeping government action to combat the spread of the Depression that his successor Franklin Roosevelt did. As a result, his name has become associated with the Depression, perhaps a bit unfairly. 

What are diuretics?

Indications and Procedures

The basic functional unit of the kidney is the nephron. It consists of four regions: glomerulus, proximal convoluted tubule, loop of Henle, and distal convoluted tubule. The purpose of the nephron is to filter waste products from the blood and excrete these products as urine. Blood filtering occurs in the glomerulus. In the adult, approximately 180 liters of filtrate is produced daily. The purpose of the other three segments of the nephron are to reabsorb the majority of water and electrolytes from the filtrate and return these items to circulation, leaving approximately 1.8 liters to be discarded as urine.

In certain disease states it becomes necessary to enhance urine production to relieve symptoms and prevent morbidity (illness) or mortality (death). Increased urine production can be accomplished by the administration of a category of drugs known as diuretics. Diuretics are prescription medications that work by blocking the reabsorption of solutes, especially salt (sodium) and water, which passively follows sodium. Thus, solutes and water are excreted from the body rather than being returned to circulation. Diuretics are prescribed for conditions such as high blood pressure (hypertension), heart failure, pulmonary
edema, kidney (renal) failure, and liver (hepatic) failure or cirrhosis with accompanying fluid in the abdominal cavity (ascites). Diuresis results in a lower blood volume and reduces blood pressure and the work of the heart. By removing fluid from the lungs breathing is less labored. Diuretics also maintain urine production in shock states. This prevents acute renal failure. Removing abdominal fluid makes it easier to breathe and comfort of the individual is increased.

The care provider will prescribe diuretic therapy after examining a patient and obtaining supporting information such as blood pressure, radiological examinations, and laboratory tests. The patient’s lifestyle, preferences, and the cost of medications are considered in the decision to prescribe diuretics and which type of diuretics to prescribe.

Uses and Complications

There are four major types of diuretics: high-ceiling, thiazide, potassium-sparing, and osmotic diuretics. The most potent are high-ceiling agents (for example, furosemide). These drugs are commonly referred to as loop diuretics because they exert effects on the loop of Henle portion of the nephron. Administration of loop diuretics may result in profound fluid and electrolyte loss. This can lead to serious side effects such as low blood volume (hypovolemia), low blood pressure (hypotension), and electrolyte and acid-base disturbances requiring treatment. Loop diuretics are ototoxic and can lead to hearing loss. Hearing loss may be reversed if reported to the care provider and the medication is stopped. An advantage of loop diuretics is that they continue to work even if renal blood flow is decreased. This is not true with other types of diuretics.

Another class of diuretic agents is the thiazides (for example, hydrochlorothiazide). Thiazides exert their effects on the proximal portion of the distal convoluted tubule. Although not as potent as high-ceiling diuretics they produce losses of electrolytes and water. Thiazide diuretics do not cause as much calcium excretion as loop diuretics and are useful in patients prone to calcium kidney stones. They suppress insulin production and glycogen storage resulting in higher blood glucose levels. This requires diabetic patients receiving thiazide diuretics to monitor blood glucose closely. Thiazides also decrease the excretion of uric acid. As uric acid blood levels rise, gout may develop. This class of diuretics is relatively inexpensive and well tolerated and is often used as first-line therapy for hypertension.

Potassium-sparing diuretics exert only a modest increase in urine output. There are two types of potassium-sparing agents: aldosterone antagonists (for example, spironalactone) and non-aldosterone antagonists (for example, amiloride). Aldosterone, a hormone secreted by the adrenal gland, increases sodium and water reabsorption in the nephron. By blocking aldosterone the reuptake of sodium and water is prohibited. Aldosterone antagonists require approximately forty-eight hours to demonstrate an effect. Non-aldosterone antagonists directly inhibit sodium and water reabsorption and effects begin without delay. Potassium-sparing diuretics cause minimal amounts of potassium to be lost in the urine. This class of diuretics is frequently used with loop or thiazide diuretics, not for diuresis, but to prevent potassium depletion. Side effects include too much potassium in the body (hyperkalemia) resulting in fatal heart rhythms, and endocrine effects. Because aldosterone antagonists are steroid hormones
gynecomastia, menstrual irregularities, impotence, hirsutism, and deepening of the voice may occur. Potassium-sparing diuretics should not be taken with other drugs which are potassium sparing
(angiotensin-converting enzyme inhibitors, angiotensin receptor blockers, or direct renin inhibitors), potassium supplements, or salt substitutes containing potassium.

Osmotic diuretics are the final class of diuretic agents (for example, mannitol). Osmotic agents differ from other diuretic groups in their mechanism of action and indications for use. Osmotic drugs work by creating an osmotic force. When utilized to maintain urine production and prevent renal failure in patients suffering from shock, the drug is administered intravenously. In the kidney, the osmotic agent is freely filtered from the blood into the filtrate. It remains in the filtrate and holds water close to it in an attempt to maintain a normal solute-solvent ratio. The degree of diuresis is directly proportional to the concentration of osmotic agent in the filtrate. In treating increased pressure within the eye (intraocular pressure) as in glaucoma, osmotic eye drops work the same way—they create an osmotic force thus reducing pressure within the eye.

Diuretic drugs should be used with caution in patients with diabetes, gout, or renal impairment; during pregnancy; and when taking other drugs such as digoxin, lithium, ototoxic medications, nonsteroidal anti-inflammatory drugs (NSAIDs), or additional antihypertensive agents. Individuals should weigh daily in the morning before eating or drinking and keep a weight record that should be shared with the care provider. Also, they should check and record the blood pressure as instructed and remain alert to side effects of dehydration (dry mouth, thirst, low urine output), low potassium levels (irregular heartbeat, muscle weakness, cramping), or high potassium levels (slow or irregular heartbeat, high muscle tone, tingling).

Perspective and Prospects

Control of fluid and electrolytes to treat pathologic conditions such as hypertension, heart failure, pulmonary edema, and ascites is not new. Historical references go back to ancient Egypt. Throughout the centuries various medications to control these pathologies have been utilized including plants and herbs, and in the 1940s, mercury compounds. Thiazide diuretics were introduced in 1958 followed by the loop diuretic furosemide in 1966. Since that time additional diuretics have been invented. As the rate of obesity, type 2 diabetes mellitus, and hypertension continue to rise in the United States the need for diuretic agents will increase. Pharmaceutical companies consider new compounds that may show benefit as the next diuretic agent.

Bibliography

Adams, Michael, and Robert Koch. “Diuretic Therapy and the Pharmacotherapy of Renal Failure.” In Pharmacology: Connections to Nursing Practice. Upper Saddle River, N.J.: Pearson, 2010.

Broyles, Bonita, Barry Reiss, and Mary Evans, eds. Pharmacological Aspects of Nursing Care. 8th ed. Clifton Park, N.Y.: Cengage Learning, 2013.

Herbert-Ashton, Marilyn, and Nancy Clarkson, eds. Pharmacology. 2d ed. Sudbury, Mass.: Jones and Bartlett, 2008.

Mayo Clinic. "Diuretics." Mayo Clinic, December 16, 2010.

Will, Julie. “Diuretic Therapy and Drugs for Renal Failure.” In Pharmacology for Nurses: A Pathophysiologic Approach, edited by Michael Adams, Leland Holland, Jr., and Paula Bostwick. Upper Saddle River, N.J.: Pearson-Prentice Hall, 2008.