Considere a velocidade da luz no ar 3 x 10⁸ m/s e a velocidade do som no ar 340 m/s. Um observador vê um relâmpago e, 3 segundos
depois, ele escuta o trovão correspondente. A distância que o observador está do ponto em que caiu o raio é de aproximadamente

Um sistema massa-mola, com constante de mola igual a 40 N/m, realiza um movimento harmônico simples. A energia cinética, no ponto médio entre a posição de aceleração máxima e velocidade máxima, é igual a 0,1J. Sabendo que a velocidade máxima é igual a 2 m/s, a aceleração máxima é igual a

Dado: Considere !$ \sqrt{6} = \dfrac{5}{2} !$

‘Diplomatics, from ______ Greek diploma (folded), is ____ study of legal and administrative documents of all kinds. Most attention has been paid to ______ public documents of monarchs, emperors, and popes, which are usually classified separately from_____ many varieties of private documents that exist.’ (CRYSTAL, David (2010). The Cambridge Encyclopedia of Language. Cambridge University Press).

The blanks of this excerpt can be adequately filled by:

A diferença entre o comprimento x e a largura y de um retângulo é de 2cm. Se a sua área é menor ou igual a 35cm², então o valor de x, em cm, será:

Um bloco de massa igual a 500 g está em repouso diante de uma mola ideal com constante elástica de 1,1 x 10⁴ N/m e será lançado pela mola para atingir o anteparo C com velocidade de 10 m/s. O percurso, desde a mola até o anteparo C, é quase todo liso, e apenas o trecho de 5 m que vai de A até B possui atrito, com coeficiente igual a 0,8. Então, a compressão da mola deverá ser

O valor da soma de a e b, para que a divisão de !$ f(x)=x^3+ax+b !$ por !$ g(x) = 2x^2 + 2x - 6 !$ seja exata, é

Seja ax + by + cz + d + 0 a equação do plano que passa pelos pontos (4, - 2, 2) e (1, 1, 5) e é perpendicular ao plano 3x – 2y + 5z – 1 = 0.

A razão !$ \dfrac{d}{b} !$ é

Choose the correct alternative.

This is not installed correctly. They____________ my instructions.

There are two options for the sentences below, choose the ONLY one that both options are possible.

TEXT 1

Royal Navy hands fishing boat to Yemen authorities in counter-piracy operation

An elite team of Royal Marines stormed the fishing vessel on Friday, seizing it back from a gang of suspected Somali pirates. The pirates are believed to have stolen the fishing vessel in order to use it as a platform for launching hijack attempts on cargo ships and tankers in the Gulf of Aden.

The return of the fishing vessel – known as a dhow – is part of the NATO (North Atlantic Treaty Organization) crackdown on piracy in the seas around Somalia. Captain Gerry Northwood, who is heading the counter-piracy operation on board RFA Fort Victoria, said that he was pleased to return the dhow to her Yemeni owner. “This was a good example of Royal Navy and the Yemeni Navy working together for the common good of the local maritime community”, he said. “I was pleased that we were able to return the dhow to its rightful owner. It is important that through our cooperation with the Yemeni Navy, we reassure the local maritime community that we are able to protect their interests. They are as much the victims of Somali piracy as the larger international ships navigating through the area". The dhow was handed over to the Yemeni Navy. A spokesman said “Thank you for the dhow and thank you for everything”.

Piracy in the Indian Ocean currently costs the world economy billions of pounds a year. Merchant vessels are being forced into large detours around dangerous areas and insurance costs have risen.

(Adapted from www.telegraph.co.uk/news/worldnews/piracy/ Jan 17,2012)

TEXT 2

Seven dead in Genoa shipping accident

Up to eight people are feared dead after a massive cargo ship rammed into a control tower in the Italian port of Genoa during a night-time manoeuvre that went wrong. The collision sent the 165ft-tall cement control tower crashing to the ground, with much of its mangled remains tumbling into the harbour. Around 14 people were in the glass-topped tower when it was hit by the ship’s stern as it ploughed into the dock. Some were thrown into the water, while others were trapped under rubble or in a lift which may have toppled into the sea.

A 50-year-old man was reportedly pulled alive from the rubble 12 hours after the accident and taken to hospital while seven bodies were recovered -several by rescue divers from the water, the police said. It is unclear how many are still missing.

The vast red ship, which has a gross tonnage of more than 40,500, was following the protocol and navigating towards the control tower when it failed to reverse properly before turning out into the open sea. It rammed into the concrete and metal structure. As rescue workers and sniffer dogs searched through the rubble for survivors, the death toll steadily increased. Four people were still missing, with some believed to be trapped in the wrecked internal lift in the tower. The collision happened during a change of shift, meaning that there were more people in the tower than normal. The 655ft-long Jolly Nero cargo ship was leaving Genoa’s port, the biggest and busiest in north-western Italy. The vessel has been impounded and investigators have opened an investigation. The captain has been detained for questioning.

(Adapted from www.telegraph.co.uk / May 08, 2013)

The prefix un as in ‘unclear’ (line 17) is used correctly in all alternatives EXCEPT: