(UEFS) Uma esfera, A, com massa de 50,0g e velocidade de 8,0 m/s choca-se frontalmente com outra esfera, B, que se encontra em repouso sobre uma superfície plana e horizontal de atrito desprezível. Sabendo-se que a massa da esfera B é de 200,0g e que o choque é perfeitamente elástico, os módulos das velocidades das esferas A e B, após o choque, em m/s, são iguais, respectivamente, a

Texto base:  

Enunciado:

a) Explique o que foi o Código de Hamurabi, criado durante o Império Babilônico.

b) Cite o principal objetivo do Código de Hamurabi.

(AFA) THE RELATIONSHIP BETWEEN FRIENDS AND TYPES OF FRIENDSHIP

Everyone has at least one best friend, some maybe even more. There are also those people who are just friends and also arch-enemies. People may think that just because they are your friends it means that they are your best friend. The thing is, even though they are your friend, the relationship between a best friend and a friend is different. Either way regardless of archenemies, friends or best friends, there are not many ways to compare any of these different types of friends, but you can easily contrast them from one another.

Arch-enemies often know more about each other than two friends. In a comparison of personal relationships, ¹friendship is considered to be closer than association, although a wide range of degrees of intimacy exists in friendships, arch-enemies, and associations. Friendship and association can be thought of as spanning across the same continuum. ²The study of friendship is included in the fields of sociology, social psychology, anthropology, philosophy, and zoology. Even animals have familiars! Various academic theories of friendship have been proposed, among which are social exchange theory, equity theory, relational dialectics, and attachment styles. ³In Russia, one typically bestows very few people the status of “friend”.

These friendships, however, make up in intensity what they lack in number. Friends are entitled to call each other by their first names alone, and to use diminutives. A customary example of polite behavior is addressing "acquaintances" by full first name plus their patronymic. These could include relationships which elsewhere would be qualified as real friendships, such as workplace relationships of long standing, or neighbors with whom one shares an occasional meal or a social drink with.

Also in the Middle East and Central Asia, male friendships, while less restricted than in Russia, tend to be reserved and respectable in nature. They may use nicknames and diminutive forms of their first names. In countries like India, it is believed in some parts that friendship is a form of respect, not born out of fear or superiority. Friends are people who are equal in most standards, but still respect each other regardless of their attributes or shortcomings. Most of the countries previously mentioned (Russia, Asia, and even the Middle East) and even our own nation are suffering a decline in genuine friendships.

According to a study documented in the June 2006 issue of the Journal American Sociological Review, Americans are thought to be suffering a loss in the quality and quantity of close friendships since at least 1985. The study’s results state that twenty-five percent of ⁴Americans have no close confidants, and the average total number of confidants per citizen has dropped from four to two. According to the study, ⁵Americans' dependence on family as a safety net went up from fifty-seven percent to eighty percent; Americans dependence on a partner or spouse went up from five percent to nine percent.

Recent studies have found a link between fewer friendships, especially in quality, and psychological and physiological regression. In the sequence of the emotional development of the individual, friendships come after parental bonding and before the pair bonding engaged in at the approach of maturity. In the intervening period between the end of early childhood and the onset of full adulthood, friendships are often the most important relationships in the emotional life of the adolescent, and are often more intense than relationships experienced later in life.

⁶Unfortunately, making friends seems to trouble many of people. Having no friends can be emotionally damaging for all ages, from young children to full grown adults. A study performed by researchers from Purdue University found that post-secondary-education friendships, college and university last longer than the friendships before it. Children with Asperger syndrome and autism usually have some difficulty forming friendships. ⁷Socially crippling conditions like these are just one way that the social world is so difficult to thrive in. ⁸This does not mean that they are not able to form friendships, however. With time, moderation and proper instruction, they are able to form friendships after realizing their own strengths and weaknesses.

⁹There is a number of theories that attempt to explain the link, including that; Good friends encourage their friends to lead more healthy lifestyles; ¹⁰Good friends encourage their friends to seek help and access services, when needed; ¹¹Good friends enhance their friend’s ¹²coping skills in dealing with illness and other health problems; and/or Good friends actually affect physiological pathways that are protective of health. Regardless of what we think, we can clearly see that there are some ways that friends, best friends and archenemies are the same, but in the end they are clearly more different. ¹³Nonetheless we all have every single type in our lives.

(Adapted from: http://www.ukessays.com/essays/philosophy/therelationship- between-friends-and-types-of-friendship-philosophyessay. php) 

“This does not mean that they are not able to form friendships, however” (reference 8). The option that replaces the highlighted expression is 

(UFPR) Capacitores são dispositivos que podem armazenar energia quando há um campo elétrico em seu interior, o qual é produzido por cargas elétricas depositadas em suas placas. O circuito ao lado é formado por um capacitor C de capacitância 2 μF e por duas fontes de fem, consideradas ideais, com  e 

Observe o sistema formado por um bloco de massa  comprimindo uma mola de constante  representado na figura abaixo.

Considere a mola como sem massa e o coeficiente de atrito cinético entre o bloco e a superfície igual a  µ_C

Qual deve ser a compressão X da mola para que o bloco deslize sem rolar sobre a superfície horizontal e pare no ponto distante 4x da posição de equilíbrio da mola?