(UNIT) A equação horária do espaço, em função do tempo, do movimento realizado por um móvel é dada por S = 10t -2t², no SI.

Com base nessa informação, analise as afirmativas e marque com V as verdadeiras e com F, as falsas.

( ) O movimento descrito é retrógrado e retardado.

( ) O móvel realiza movimento progressivo e retardado.

( ) A equação horária da velocidade é igual a v = 10 - 2t.

( ) O móvel passa pela origem do espaço no instante igual a 5,0 s.

A alternativa que indica a sequência correta, de cima para baixo, é a 

Em uma área de construção civil, uma máquina a 20 metros de altura e em mau funcionamento arremessou para baixo um tijolo de 4 kg de massa com velocidade inicial de 5 m/s e sob efeito da aceleração da gravidade de 10 m/s2, fazendo com que o objeto chegasse ao chão com velocidade de 15 m/s.

A quantidade de energia mecânica dissipada durante a queda do tijolo foi

(UERN) Mooresville’s Shining Example (It’s Not Just About the Laptops)

MOORESVILLE, N.C. — Sixty educators from across the nation roamed the halls and ringed the rooms of East Mooresville Intermediate School, searching for the secret formula. They found it in Erin Holsinger’s fifth-grade math class.

There, a boy peering into his school-issued MacBook blitzed through fractions by himself, determined to reach sixth-grade work by winter. Three desks away, a girl was struggling with basic multiplication – only 29 percent right, her screen said – and Ms. Holsinger knelt beside her to assist. Curiosity was fed and embarrassment avoided, as teacher connected with student through emotion far more than Wi-Fi.

As debate continues over whether schools invest wisely in technology – and whether it measurably improves student achievement – Mooresville, a modest community about 20 miles north of Charlotte best known as home to several Nascar teams and drivers, has quietly emerged as the de facto national model of the digital school.

The district’s graduation rate was 91 percent in 2011, up from 80 percent in 2008. On state tests in reading, math and science, an average of 88 percent of students across grades and subjects met proficiency standards, compared with 73 percent three years ago. Attendance is up, dropouts are down. Mooresville ranks 100th out of 115 districts in North Carolina in terms of dollars spent per student – $7,415.89 a year – but it is now third in test scores and second in graduation rates.

“Other districts are doing things, but what we see in Mooresville is the whole package: using the budget, innovating, using data, involvement with the community and leadership,” said Karen Cator, a former Apple executive who is director of educational technology for the United States Department of Education. “There are lessons to be learned.”

Start with math lessons: each student’s MacBook Air is leased from Apple for $215 a year, including warranty, for a total of $1 million; an additional $100,000 a year goes for software. Terry Haas, the district’s chief financial officer, said the money was freed up through “incredibly tough decisions.”

Sixty-five jobs were eliminated, including 37 teachers, which resulted in larger class sizes – in middle schools, it is 30 instead of 18 – but district officials say they can be more efficiently managed because of the technology. Some costly items had become obsolete (like computer labs), though getting rid of others tested the willingness of teachers to embrace the new day: who needs globes in the age of Google Earth?

Families pay $50 a year to subsidize computer repairs, though the fee is waived for those who cannot afford it, about 18 percent of them. Similarly, the district has negotiated a deal so that those without broadband Internet access can buy it for $9.99 a month. Mr. Edwards said the technology had helped close racial performance gaps in a district where 27 percent of the students are minorities and 40 percent are poor enough to receive free or reduced-price lunches.

(The New York Times. February 13, 2012/adaptado) 

The underlined word in the text refers to:

Uma bola branca de sinuca, com velocidade de 10 m/s na direção X e sentido positivo, colide elasticamente, na origem do sistema de coordenadas XY, com uma bola preta de mesma massa, inicialmente em repouso.

Após a colisão, as velocidades finais das bolas preta, VF_P, e branca, VF_B, são, respectivamente, em m/s, iguais a:

(UNICENTRO) O princípio de conservação dos alimentos por meio do sal baseia-se nos conhecimentos sobre transportes de substâncias através da membrana plasmática. Em alimentos conservados em alta concentração de sal, os micro-organismos morrem por desidratação, pois a água do seu citoplasma atravessa rapidamente para o meio externo à célula, em direção ao sal incorporado ao alimento.

Com base nas informações e de acordo com os conhecimentos relacionados ao transporte de substâncias através da membrana plasmática, pode-se afirmar: