Uma corda de massa 100 g vibra com uma frequência de 200 Hz como está descrito na figura a seguir:
O produto da força tensora com o comprimento da corda, em N.m deve ser de:
Questões relacionadas
- Química | 2.1 Soluções e Coloides
(FAMERP) A mistura conhecida como soro fisiológico é um exemplo de __________, na qual o __________ é a água e o __________ é o __________ de sódio.
As lacunas do texto são, correta e respectivamente, preenchidas por:
- Matemática | 13.6. Circunferência
(FGV) Na figura, AB e AE são tangentes à circunferência nos pontos B e E, respectivamente, e BÂE = 60º.
Se os arcos BPC, CQD e DRE têm medidas iguais, a medida do ângulo BÊC, indicada na figura por α, é igual a
- Química | 2.6 Eletroquímica
(IFSUL) Pilhas são dispositivos que transformam energia química em energia elétrica por meio de um sistema montado para aproveitar o fluxo de elétrons provenientes de uma reação química de oxirredução, conforme mostra o seguinte exemplo.
Considerando que os Potenciais de redução do Níquel e do Zinco são, respectivamente, - 0,25 V e - 0,76 V, é correto afirmar que:
- Física | A. Grandezas, Potência e Energia Elétrica
(UNIT MACEIÓ) O raio, uma descarga natural, necessita que exista uma tensão média de 2,5.107V entre dois pontos da atmosfera para que seja produzido. Nessa situação, o valor da corrente é da ordem de 2.105A. Considere que o intervalo para que aconteça a descarga seja de, aproximadamente,10-3s.
Nessas condições, a energia liberada durante a produção de um raio é igual, em joule, a
- Língua Inglesa | 2.01 Pronomes
(UNIFESP) The Rise of Antibiotic Resistance
By The Editorial Board
May 10, 2014
The World Health Organization has surveyed the growth of antibiotic-resistant germs around the world – the first such survey it has ever conducted – and come up with disturbing findings. In a report issued late last month, the organization found that antimicrobial resistance in bacteria (the main focus of the report), fungi, viruses and parasites is an increasingly serious threat in every part of the world. “A problem so serious that it threatens the achievements of modern medicine,” the organization said. “A post-antibiotic era, in which common infections and minor injuries can kill, far from being an apocalyptic fantasy, is instead a very real possibility for the 21st century.”
The growth of antibiotic-resistant pathogens means that in ever more cases, standard treatments no longer work, infections are harder or impossible to control, the risk of spreading infections to others is increased, and illnesses and hospital stays are prolonged. All of these drive up the costs of illnesses and the risk of death. The survey sought to determine the scope of the problem by asking countries to submit their most recent surveillance data (114 did so). Unfortunately, the data was glaringly incomplete because few countries track and monitor antibiotic resistance comprehensively, and there is no standard methodology for doing so.
Still, it is clear that major resistance problems have already developed, both for antibiotics that are used routinely and for those deemed “last resort” treatments to cure people when all else has failed. Carbapenem antibiotics, a class of drugs used as a last resort to treat life-threatening infections caused by a common intestinal bacterium, have failed to work in more than half the people treated in some countries. The bacterium is a major cause of hospital-acquired infections such as pneumonia, bloodstream infections, and infections in newborns and intensive-care patients. Similarly, the failure of a last-resort treatment for gonorrhoea has been confirmed in 10 countries, including many with advanced health care systems, such as Australia, Canada, France, Sweden and Britain. And resistance to a class of antibiotics that is routinely used to treat urinary tract infections caused by E. coli is widespread; in some countries the drugs are now ineffective in more than half of the patients treated. This sobering report is intended to kick-start a global campaign to develop tools and standards to track drug resistance, measure its health and economic impact, and design solutions.
The most urgent need is to minimize the overuse of antibiotics in medicine and agriculture, which accelerates the development of resistant strains. In the United States, the Food and Drug Administration (FDA) has issued voluntary guidelines calling on drug companies, animal producers and veterinarians to stop indiscriminately using antibiotics that are important for treating humans on livestock; the drug companies have said they will comply. But the agency, shortsightedly, 1has appealed a court order requiring it to ban the use of penicillin and two forms of tetracycline by animal producers to promote growth unless they provide proof that it will not promote drug-resistant microbes.
The pharmaceutical industry needs to be encouraged to develop new antibiotics to supplement those that are losing their effectiveness. The Royal Pharmaceutical Society, which represents pharmacists in Britain, called this month for stronger financial incentives. It said that no new class of antibiotics has been discovered since 1987, largely because the financial returns for finding new classes of antibiotics are too low. Unlike lucrative drugs to treat chronic diseases like cancer and cardiovascular ailments, antibiotics are typically taken for a short period of time, and any new drug is apt to be used sparingly and held in reserve to treat patients resistant to existing drugs. Antibiotics have transformed medicine and saved countless lives over the past seven decades. Now, rampant overuse and the lack of new drugs in the pipeline threaten to undermine their effectiveness.
(www.nytimes.com. Adaptado.)
No trecho do quarto parágrafo (ref. 1), “has appealed a court order requiring it to ban the use of penicillin”, o termo em destaque se refere a: