{"id":89,"date":"2014-11-18T12:34:11","date_gmt":"2014-11-18T12:34:11","guid":{"rendered":"http:\/\/fisicaevestibular.com.br\/novo\/?page_id=89"},"modified":"2024-09-02T16:39:38","modified_gmt":"2024-09-02T16:39:38","slug":"resolucao-comentada-da-afa-2015","status":"publish","type":"page","link":"https:\/\/fisicaevestibular.com.br\/novo\/universidades-2015\/exercicios-da-afa-2015\/resolucao-comentada-da-afa-2015\/","title":{"rendered":"Resolu\u00e7\u00e3o comentada da AFA 2015"},"content":{"rendered":"

RESOLU\u00c7\u00d5ES<\/span><\/span><\/span><\/p>\n

01- <\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

\"\"<\/p>\n

\"\"<\/p>\n

R- A<\/b><\/span><\/span><\/span><\/p>\n

02- <\/span><\/span><\/span>A caixa de <\/b><\/span><\/span>massa <\/b><\/span><\/span><\/span>m<\/b><\/span><\/span><\/span> sobre o caminh\u00e3o est\u00e1 descrevendo uma curva de <\/b><\/span><\/span><\/span>raio R<\/b><\/span><\/span><\/span>, <\/b><\/span><\/span>com atrito <\/b><\/span><\/span><\/span>entre a caixa e o assoalho da carroceria.<\/b><\/span><\/span><\/p>\n

Como a <\/b><\/span><\/span>estrada \u00e9 horizontal as for\u00e7as <\/b><\/span><\/span><\/span>peso e normal se anulam.<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

Nesse caso, a <\/b><\/span><\/span>for\u00e7a horizontal que evita que caixa derrape <\/b><\/span><\/span><\/span>(saia pela tangente) \u00e9 a <\/b><\/span><\/span>for\u00e7a de atrito<\/b><\/span><\/span><\/span><\/p>\n

\"\"que \u00e9 a pr\u00f3pria resultante centr\u00edpeta\"\"\u00a0, ou seja,\u00a0\"\" =\"\"<\/b><\/span><\/span><\/span>— <\/b><\/span><\/span>F<\/b><\/span><\/span><\/span>c<\/b><\/span><\/span><\/sub><\/span>=F<\/b><\/span><\/span><\/span>at<\/b><\/span><\/span><\/sub><\/span>=m.V<\/b><\/span><\/span><\/span>2<\/b><\/span><\/span><\/sup><\/span>\/R.<\/b><\/span><\/span><\/span><\/p>\n

A for\u00e7a de <\/b><\/span><\/span>atrito <\/b><\/span><\/span><\/span>est\u00e1tico<\/b><\/span><\/span><\/span> ser\u00e1 m\u00e1xima quando a caixa estiver na <\/b><\/span><\/span><\/span>imin\u00eancia\u00a0 de escorregar <\/b><\/span><\/span><\/span>para fora da carroceria<\/b><\/span><\/span><\/span>e nesse caso <\/b><\/span><\/span>F<\/b><\/span><\/span><\/span>atem\u00e1ximo<\/b><\/span><\/span><\/sub><\/span>=\u03bc<\/b><\/span><\/span><\/span>e<\/b><\/span><\/span><\/sub><\/span>N=\u03bc<\/b><\/span><\/span><\/span>e<\/b><\/span><\/span><\/sub><\/span>P=\u03bc<\/b><\/span><\/span><\/span>e<\/b><\/span><\/span><\/sub><\/span>mg\u00a0 <\/b><\/span><\/span><\/span>—\u00a0 <\/b><\/span><\/span>F<\/b><\/span><\/span><\/span>c<\/b><\/span><\/span><\/sub><\/span>=F<\/b><\/span><\/span><\/span>atm\u00e1x<\/b><\/span><\/span><\/sub><\/span>\u00a0 <\/b><\/span><\/span><\/span>—\u00a0 mV<\/b><\/span><\/span>2<\/b><\/span><\/span><\/sup>\/R=\u03bc<\/b><\/span><\/span>e<\/b><\/span><\/span><\/sub>mg\u00a0 — V<\/b><\/span><\/span>2<\/b><\/span><\/span><\/sup>\/R=\u03bc<\/b><\/span><\/span>e<\/b><\/span><\/span><\/sub>g\u00a0<\/b><\/span><\/span><\/p>\n

\"\", que \u00e9 a <\/b><\/span><\/span>m\u00e1xima velocidade com que a caixa consegue fazer a curva sem derrapar<\/b><\/span><\/span><\/span>.<\/b><\/span><\/span><\/p>\n

S\u00e3o dados:<\/b><\/span><\/span><\/span><\/p>\n

R=51,2m<\/b><\/span><\/span><\/span><\/p>\n

O coeficiente de atrito que voc\u00ea deve utilizar \u00e9 o <\/b><\/span><\/span><\/span>maior fornecido (est\u00e1tico) <\/b><\/span><\/span><\/span>que ocorre quando a caixa est\u00e1 na <\/b><\/span><\/span><\/span>imin\u00eancia de escorregar<\/b><\/span><\/span><\/span>— \u03bc<\/b><\/span><\/span><\/span>e<\/b><\/span><\/span><\/sub><\/span> = 0,5.<\/b><\/span><\/span><\/span><\/p>\n

g=10m\/s<\/b><\/span><\/span><\/span>2<\/b><\/span><\/span><\/sup><\/span><\/p>\n

V<\/b><\/span><\/span><\/span>m\u00e1xima<\/b><\/span><\/span><\/sub><\/span> = ?<\/b><\/span><\/span><\/span><\/p>\n

V = \u221a(\u03bc<\/b><\/span><\/span><\/span>e<\/b><\/span><\/span><\/sub><\/span>.R.g) <\/b><\/span><\/span><\/span>= \u221a(0,5.51,2.10) — V=\u221a256 —<\/b><\/span><\/span>V=16m\/s.<\/b><\/span><\/span><\/span><\/p>\n

R- B<\/b><\/span><\/span><\/span><\/p>\n

03- \"\"<\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

Observe que as <\/b><\/span><\/span>duas esferas de massas m<\/b><\/span><\/span><\/span>1<\/b><\/span><\/span><\/sub><\/span> e m<\/b><\/span><\/span><\/span>2<\/b><\/span><\/span><\/sub><\/span>chegam <\/b><\/span><\/span>\u00e0 base de cada rampa com a mesma velocidade <\/b><\/span><\/span><\/span>V<\/b><\/span><\/span><\/span>1<\/b><\/span><\/span><\/sub><\/span> = V<\/b><\/span><\/span><\/span>2<\/b><\/span><\/span><\/sub><\/span> = V.<\/b><\/span><\/span><\/span><\/p>\n

Quando elas chegam \u00e0 base com <\/b><\/span><\/span>velocidade V<\/b><\/span><\/span><\/span>, j\u00e1 que <\/b><\/span><\/span>n\u00e3o existe atrito entre a base das rampas e o piso<\/b><\/span><\/span><\/span>, a <\/b><\/span><\/span>rampa A, de massa 1kg, se desloca para a direita com velocidade V<\/b><\/span><\/span><\/span>A<\/b><\/span><\/span><\/sub><\/span> e a B, de massa 2kg, para a esquerda com velocidade – V<\/b><\/span><\/span><\/span>B<\/b><\/span><\/span><\/sub><\/span> e <\/b><\/span><\/span><\/span>como o intervalo de tempo da descida (tempo de intera\u00e7\u00e3o esferas rampas)<\/b><\/span><\/span><\/span> \u00e9 muito pequeno, aproximadamente \u221a3\/2\u2248 0,9s, <\/b><\/span><\/span><\/span>voc\u00ea pode utilizar o <\/b><\/span><\/span><\/span>princ\u00edpio da conserva\u00e7\u00e3o da quantidade de movimento<\/b><\/span><\/span><\/span>:<\/b><\/span><\/span><\/p>\n

\"\"<\/p>\n

\"\"<\/p>\n

04- <\/span><\/span><\/span><\/p>\n

\"\"Considerando <\/b><\/span><\/span>d<\/b><\/span><\/span><\/span>A<\/b><\/span><\/span><\/sub><\/span> como sendo o <\/b><\/span><\/span><\/span>deslocamento do \u00eambolo A <\/b><\/span><\/span><\/span>e <\/b><\/span><\/span><\/span>d<\/b><\/span><\/span><\/span>B<\/b><\/span><\/span><\/sub><\/span> como sendo o <\/b><\/span><\/span><\/span>deslocamento do \u00eambolo B, <\/b><\/span><\/span><\/span>possuindo o l\u00edquido um volume constante, ou seja, com um <\/b><\/span><\/span>l\u00edquido incompress\u00edvel<\/b><\/span><\/span><\/span>, teremos que o um <\/b><\/span><\/span>volume l\u00edquido que desce at\u00e9 A, \u00e9 o mesmo volume l\u00edquido que sobe at\u00e9 B.\u00a0<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

\"\"<\/p>\n

05- <\/span><\/span><\/span>(01) <\/b><\/span><\/span><\/span>Um recipiente com <\/b><\/span><\/span>dilata\u00e7\u00e3o desprez\u00edvel <\/b><\/span><\/span><\/span>cont\u00e9m certa massa de \u00e1gua na <\/b><\/span><\/span>temperatura de 1\u00b0C<\/b><\/span><\/span><\/span>, quando \u00e9, ent\u00e3o, <\/b><\/span><\/span>aquecido lentamente, sofrendo uma varia\u00e7\u00e3o de temperatura <\/b><\/span><\/span><\/span>de 6 \u00b0C <\/b><\/span><\/span><\/span>. Nesse caso, o <\/b><\/span><\/span>volume da \u00e1gua primeiro aumenta e depois diminui. <\/b><\/span><\/span><\/span><\/p>\n

(01) Falsa—<\/b><\/span><\/span><\/span>A <\/b><\/span>\u00e1gua n\u00e3o se comporta termicamente como a maioria dos l\u00edquidos<\/b><\/span><\/span>. Para analisar esse comportamento, imagine que <\/b><\/span>certa quantidade de \u00e1gua a <\/b><\/span><\/span>0 \u00b0C <\/b><\/span><\/span>\u00e9 colocada em um recipiente praticamente n\u00e3o se dilate. <\/b><\/span>Aumentando a t<\/b><\/span><\/span>emperatura<\/b><\/span><\/span>, o <\/b><\/span><\/span>volume do l\u00edquido diminui <\/b><\/span><\/span>at\u00e9 a temperatura atingir <\/b><\/span><\/span>4 \u00b0C. <\/b><\/span><\/span>A partir da\u00ed, se o <\/b><\/span>aquecimento continua, o volume do l\u00edquido passa a aumentar<\/b><\/span><\/span>. A conclus\u00e3o que se pode tirar desse efeito \u00e9 a de que, no <\/b><\/span>aquecimento de 0 \u00b0C a 4 \u00b0C, a \u00e1gua sofre contra\u00e7\u00e3o<\/b><\/span><\/span>. No <\/b><\/span>aquecimento acima de 4 \u00b0C, ocorre dilata\u00e7\u00e3o <\/b><\/span><\/span>(veja gr\u00e1fico 1 abaixo).<\/b><\/span><\/span><\/p>\n

\"\"<\/p>\n

Veja na express\u00e3o <\/b><\/span>d = m\/V<\/b><\/span><\/span>que, sendo a <\/b><\/span>massa de \u00e1gua a mesma<\/b><\/span><\/span>, a <\/b><\/span>densidade (d) \u00e9 inversamente proporcional ao volume (V) <\/b><\/span><\/span>e, assim a <\/b><\/span>um volume m\u00ednimo que ocorre a 0<\/b><\/span><\/span>o<\/b><\/span><\/sup><\/span>C corresponde uma densidade m\u00e1xima, tamb\u00e9m a 0<\/b><\/span><\/span>o<\/b><\/span><\/sup><\/span>C <\/b><\/span><\/span>(veja gr\u00e1fico 2 acima).<\/b><\/span><\/span><\/p>\n

02)<\/b><\/span><\/span><\/span>Quando se <\/b><\/span><\/span>aquece uma placa met\u00e1lica que apresenta um <\/b><\/span><\/span><\/span>orif\u00edcio<\/b><\/span><\/span><\/span>, verifica-se que, com a <\/b><\/span><\/span>dilata\u00e7\u00e3o da placa, a \u00e1rea do orif\u00edcio aumenta.<\/b><\/span><\/span><\/span><\/p>\n

(02) Correta— <\/b><\/span><\/span><\/span>Se uma <\/b><\/span><\/span>placa met\u00e1lica com orif\u00edcio for aquecida, verifica-se que o orif\u00edcio aumenta, <\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

como se fosse constitu\u00eddo pelo material da placa, <\/b><\/span><\/span><\/span>pois tudo se passa <\/b><\/span><\/span>como se o furo tivesse um coeficiente de dilata\u00e7\u00e3o superficial igual \u00e0quele da subst\u00e2ncia da placa.\u00a0<\/b><\/span><\/span><\/span><\/p>\n

(03) <\/b><\/span><\/span><\/span>Quando um <\/b><\/span><\/span>frasco completamente cheio de l\u00edquido \u00e9 aquecido, este <\/b><\/span><\/span><\/span>transborda um pouco<\/b><\/span><\/span><\/span>. O <\/b><\/span><\/span>volume<\/b><\/span><\/span><\/span> de l\u00edquido transbordado <\/b><\/span><\/span>mede a dilata\u00e7\u00e3o absoluta do l\u00edquido. <\/b><\/span><\/span><\/span><\/p>\n

(03) Falsa— <\/b><\/span><\/span><\/span>na figura, voc\u00ea tem um tubo de vidro <\/b><\/span><\/span>graduado,<\/b><\/span><\/span><\/span>com um l\u00edquido em seu interior<\/b><\/span><\/span><\/span>. Ap\u00f3s a <\/b><\/span><\/span><\/p>\n

\"\"<\/p>\n

\u00a0dilata\u00e7\u00e3o, o aumento observado na gradua\u00e7\u00e3o da coluna l\u00edquida<\/b><\/span><\/span><\/span>(que corresponderia ao volume de l\u00edquido transbordado)<\/b><\/span><\/span><\/span>n\u00e3o corresponde ao aumento real<\/b><\/span><\/span><\/span>, pois observe que o <\/b><\/span><\/span>recipiente tamb\u00e9m se dilatou.<\/b><\/span><\/span><\/span><\/p>\n

Assim, a <\/b><\/span><\/span>dilata\u00e7\u00e3o marcada pela escala do tubo de vidro (volume transbordado)<\/b><\/span><\/span><\/span>n\u00e3o corresponde \u00e0 dilata\u00e7\u00e3o real e sim \u00e0 aparente.<\/b><\/span><\/span><\/span><\/p>\n

(04) <\/b><\/span><\/span><\/span>O <\/b><\/span><\/span>vidro pirex <\/b><\/span><\/span><\/span>apresenta <\/b><\/span><\/span>maior resist\u00eancia ao choque t\u00e9rmico <\/b><\/span><\/span><\/span>do que o <\/b><\/span><\/span>vidro comum <\/b><\/span><\/span><\/span>porque tem <\/b><\/span><\/span>menor coeficiente de dilata\u00e7\u00e3o t\u00e9rmica do que o vidro comum. <\/b><\/span><\/span><\/span><\/p>\n

(04) Correta— <\/b><\/span><\/span><\/span>se voc\u00ea tiver <\/b><\/span><\/span>dois copos de diferentes coeficientes de dilata\u00e7\u00e3o<\/b><\/span><\/span><\/span>, o de <\/b><\/span><\/span>menor <\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

coeficiente<\/b><\/span><\/span><\/span> apresenta <\/b><\/span><\/span>maior dificuldade de se quebrar quando aquecido, pois se dilata menos, <\/b><\/span><\/span><\/span>pois a dilata\u00e7\u00e3o do vidro e o coeficiente de dilata\u00e7\u00e3o s\u00e3o diretamente proporcionais).<\/b><\/span><\/span><\/span><\/p>\n

05)<\/b><\/span><\/span><\/span> Sob press\u00e3o normal, quando uma <\/b><\/span><\/span>massa de \u00e1gua \u00e9 aquecida de 0 \u00b0C at\u00e9 100 \u00b0C <\/b><\/span><\/span><\/span>sua densidade sempre aumenta.<\/b><\/span><\/span><\/span><\/p>\n

(05) Falsa— <\/b><\/span><\/span><\/span>veja (01).<\/b><\/span><\/span><\/span><\/p>\n

06)<\/b><\/span><\/span><\/span>Ao se <\/b><\/span><\/span>elevar a temperatura de um sistema constitu\u00eddo por tr\u00eas barras retas e id\u00eanticas de ferro <\/b><\/span><\/span><\/span>interligadas de modo a <\/b><\/span><\/span>formarem um tri\u00e2ngulo is\u00f3sceles, os \u00e2ngulos internos desse tri\u00e2ngulo n\u00e3o se alteram.<\/b><\/span><\/span><\/span><\/p>\n

(06) Correto— <\/b><\/span><\/span><\/span>se as arma\u00e7\u00f5es met\u00e1licas das figuras <\/b><\/span><\/span>forem de mesmo material, homog\u00eaneas e de <\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

sec\u00e7\u00e3o transversal constante e se sofrerema mesma varia\u00e7\u00e3o de temperatura<\/b><\/span><\/span><\/span>, <\/b><\/span><\/span>elas n\u00e3o se deformar\u00e3o<\/b><\/span><\/span><\/span>, os pontos de contato n\u00e3o trocar\u00e3o for\u00e7as entre si, <\/b><\/span><\/span>elas manter\u00e3o o formato inicial<\/b><\/span><\/span><\/span>, mas com <\/b><\/span><\/span>dimens\u00f5es maiores e, todos os \u00e2ngulos internos permanecer\u00e3o os mesmos<\/b><\/span><\/span><\/span>. Observe que seus comprimentos n\u00e3o se dilatam por igual, a <\/b><\/span><\/span>hipotenusa se dilata mais que os catetos<\/b><\/span><\/span><\/span>.<\/b><\/span><\/span><\/p>\n

R- D<\/b><\/span><\/span><\/span><\/p>\n

06-<\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

07- <\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

\"\"<\/p>\n

08- <\/span><\/span><\/span>C\u00e1lculo da resist\u00eancia equivalente:<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

R<\/b><\/span><\/span><\/span>eq<\/b><\/span><\/span><\/sub><\/span>=5,5\u2126.<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

\"\"<\/p>\n

09- <\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

\"\"<\/p>\n

10- <\/span><\/span><\/span>Capacitor<\/b><\/span><\/span><\/span>, <\/b><\/span><\/span>dispositivo cuja fun\u00e7\u00e3o se resume no armazenamento de energia el\u00e9trica.<\/b><\/span><\/span><\/span><\/p>\n

Capacitor plano<\/b><\/span><\/span><\/span>\u00a0\u00e9 um aparelho constitu\u00eddo por duas placas met\u00e1licas<\/b><\/span><\/span><\/span>, <\/b><\/span><\/span>em paralelo<\/b><\/span><\/span><\/span> e separadas por um meio isolante (o qual pode ser o v\u00e1cuo ou um meio\u00a0<\/b><\/span><\/span>material diel\u00e9trico, <\/b><\/i><\/span><\/span>no exerc\u00edcio \u00e9 o ar<\/b><\/i><\/span><\/span><\/span>)<\/b><\/span><\/span>.<\/b><\/i><\/span><\/span>\u00a0<\/b><\/span><\/span><\/p>\n

Cada uma dessas placas tem a mesma \u00e1rea; e a <\/b><\/span><\/span>dist\u00e2ncia que as separa \u00e9 igual a\u00a0<\/b><\/span><\/span><\/span>d<\/b><\/i><\/span><\/span><\/span>.<\/b><\/span><\/span><\/span> <\/b><\/p>\n

\"\"<\/p>\n

Ligando-se o capacitor a uma bateria, <\/b><\/span><\/span>suas placas eletrizam-se de forma quase uniforme com <\/b><\/span><\/span><\/span>cargas de mesmo m\u00f3dulo mas sinais opostos<\/b><\/span><\/span><\/span> e o campo el\u00e9trico entre elas pode ser considerado uniforme. <\/b><\/span><\/span><\/p>\n

\"\"<\/p>\n

\"\"<\/p>\n

Observe na <\/b><\/span><\/span>express\u00e3o acima<\/b><\/span><\/span><\/span> que, <\/b><\/span><\/span>sendo K, \u03b5<\/b><\/span><\/span><\/span>o,<\/b><\/span><\/span><\/sub><\/span> S e Q constantes<\/b><\/span><\/span><\/span> a <\/b><\/span><\/span>ddp (tens\u00e3o) <\/b><\/span><\/span><\/span>U <\/b><\/span><\/span><\/span>entre as placas \u00e9 <\/b><\/span><\/span><\/span>diretamente proporcional<\/b><\/span><\/span><\/span> \u00e0 dist\u00e2ncia <\/b><\/span><\/span><\/span>d<\/b><\/span><\/span><\/span> que as separa.<\/b><\/span><\/span><\/span> <\/b><\/p>\n

Como as <\/b><\/span><\/span>placas possuem cargas de <\/b><\/span><\/span><\/span>sinais opostos elas se atraem<\/b><\/span><\/span><\/span> e, inicialmente, quando s\u00e3o <\/b><\/span><\/span>lan\u00e7adas em sentidos opostos<\/b><\/span><\/span><\/span>, <\/b><\/span><\/span>elas e os carrinhos v\u00e3o diminuindo suas velocidades at\u00e9 pararem<\/b><\/span><\/span><\/span> e, <\/b><\/span><\/span>como s\u00e3o atra\u00eddos, v\u00e3o retornar com a <\/b><\/span><\/span><\/span>dist\u00e2ncia d (e consequentemente a ddp U)<\/b><\/span><\/span><\/span> variando segundo a <\/b><\/span><\/span><\/span>fun\u00e7\u00e3o <\/b><\/span><\/span><\/span>de um movimento uniformemente variado <\/b><\/span><\/span><\/span>(d=V<\/b><\/span><\/span><\/span>o<\/b><\/span><\/span><\/sub><\/span>t \u2013 at<\/b><\/span><\/span><\/span>2<\/b><\/span><\/span><\/sup><\/span>\/2) fornecida pelo gr\u00e1fico abaixo<\/b><\/span><\/span><\/span>.<\/b><\/span><\/span><\/p>\n

\"\"<\/p>\n

Assim, <\/b><\/span><\/span>esse gr\u00e1fico \u00e9 o mesmo que o de Uxt<\/b><\/span><\/span><\/span>, pois U e d s\u00e3o diretamente proporcionais.<\/b><\/span><\/span><\/span><\/p>\n

R- A<\/b><\/span><\/span><\/span><\/p>\n

11- <\/span><\/span><\/span>Quando um <\/b><\/span><\/span>solenoide \u00e9 percorrido por corrente el\u00e9trica<\/b><\/span><\/span><\/span>, a configura\u00e7\u00e3o de suas linhas de indu\u00e7\u00e3o \u00e9 obtida pela reuni\u00e3o das configura\u00e7\u00f5es <\/b><\/span><\/span>de cada espira o que equivale \u00e0 configura\u00e7\u00e3o das linhas de indu\u00e7\u00e3o de um im\u00e3 natural.<\/b><\/span><\/span><\/span><\/p>\n

O <\/b><\/span><\/span>sentido das linhas de indu\u00e7\u00e3o no solenoide \u00e9 fornecido pela regra da m\u00e3o direita aplicada em uma <\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

de suas espiras (figura 2) e<\/b><\/span><\/span><\/span> <\/b>em seu interior o campo magn\u00e9tico \u00e9 praticamente uniforme<\/b><\/span><\/span><\/span> <\/b>(figura 1<\/b><\/span><\/span><\/span>) e fora s\u00e3o linhas que saem do polo norte e chegam ao polo sul.<\/b><\/span><\/span><\/p>\n

Observe que em todos os infinitos <\/b><\/span><\/span>pontos onde est\u00e1 a espira o campo magn\u00e9tico \"\" tem dire\u00e7\u00e3o<\/b><\/span><\/span><\/span> <\/b>horizontal e sentido para a direita<\/b><\/span><\/span><\/span> (poderia ser para a esquerda).<\/b><\/span><\/span><\/p>\n

\"\"<\/p>\n

Na <\/b><\/span><\/span>espira da figura da direita acima<\/b><\/span><\/span><\/span>, voc\u00ea pode aplicar a <\/b><\/span><\/span>regra da m\u00e3o esquerda para cada trecho do fio:<\/b><\/span><\/span><\/span><\/p>\n

Regra da m\u00e3o esquerda<\/b><\/span><\/span><\/span>: O dedo <\/b><\/span><\/span>m\u00e9dio indica o sentido da corrente el\u00e9trica i,<\/b><\/span><\/span><\/span> <\/b>o indicador mostra<\/b><\/span><\/span><\/span> <\/b><\/p>\n

\"\"<\/p>\n

o sentido do campo magn\u00e9tico \"\" <\/b><\/span><\/span><\/span>e <\/b><\/span><\/span>o polegar a for\u00e7a magn\u00e9tica \"\".<\/b><\/span><\/span><\/span><\/p>\n

Intensidade da for\u00e7a magn\u00e9tica:<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

F<\/b><\/span><\/span><\/span>m<\/b><\/span><\/span><\/sub><\/span>\u00a0<\/b><\/span><\/span><\/span>\u2013 intensidade da for\u00e7a magn\u00e9tica que age sobre o fio \u2013 <\/b><\/span><\/span>medida em newton (N), no SI.<\/b><\/span><\/span><\/span><\/p>\n

B <\/b><\/span><\/span><\/span>\u2013 intensidade do campo magn\u00e9tico \u2013 <\/b><\/span><\/span>medido em tesla (T), no SI<\/b><\/span><\/span><\/span>.<\/b><\/span><\/span><\/p>\n

i <\/b><\/span><\/span><\/span>\u2013 corrente el\u00e9trica no fio \u2013 <\/b><\/span><\/span>medida em amp\u00e8re (A), no SI.<\/b><\/span><\/span><\/span><\/p>\n

\u03b8 <\/b><\/span><\/span><\/span>\u2013 <\/b><\/span><\/span>\u00e2ngulo entre a dire\u00e7\u00e3o de B e de i<\/b><\/span><\/span><\/span>.<\/b><\/span><\/span><\/p>\n

\"\"<\/p>\n

\"\"<\/p>\n

 <\/p>\n

Voltar para os Exerc\u00edcios<\/a><\/span><\/h3>\n","protected":false},"excerpt":{"rendered":"

RESOLU\u00c7\u00d5ES 01- R- A 02- A caixa de massa m sobre o caminh\u00e3o est\u00e1 descrevendo uma curva de raio R, com atrito entre a caixa e o assoalho da carroceria. Como a estrada \u00e9 horizontal as for\u00e7as peso e normal se anulam. Nesse caso, a for\u00e7a horizontal que evita que caixa derrape (saia pela tangente) \u00e9 a for\u00e7a de atrito<\/p>\n","protected":false},"author":1,"featured_media":0,"parent":87,"menu_order":0,"comment_status":"closed","ping_status":"closed","template":"","meta":{"om_disable_all_campaigns":false,"_monsterinsights_skip_tracking":false,"_monsterinsights_sitenote_active":false,"_monsterinsights_sitenote_note":"","_monsterinsights_sitenote_category":0,"footnotes":""},"class_list":["post-89","page","type-page","status-publish","hentry"],"aioseo_notices":[],"_links":{"self":[{"href":"https:\/\/fisicaevestibular.com.br\/novo\/wp-json\/wp\/v2\/pages\/89","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/fisicaevestibular.com.br\/novo\/wp-json\/wp\/v2\/pages"}],"about":[{"href":"https:\/\/fisicaevestibular.com.br\/novo\/wp-json\/wp\/v2\/types\/page"}],"author":[{"embeddable":true,"href":"https:\/\/fisicaevestibular.com.br\/novo\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/fisicaevestibular.com.br\/novo\/wp-json\/wp\/v2\/comments?post=89"}],"version-history":[{"count":1,"href":"https:\/\/fisicaevestibular.com.br\/novo\/wp-json\/wp\/v2\/pages\/89\/revisions"}],"predecessor-version":[{"id":90,"href":"https:\/\/fisicaevestibular.com.br\/novo\/wp-json\/wp\/v2\/pages\/89\/revisions\/90"}],"up":[{"embeddable":true,"href":"https:\/\/fisicaevestibular.com.br\/novo\/wp-json\/wp\/v2\/pages\/87"}],"wp:attachment":[{"href":"https:\/\/fisicaevestibular.com.br\/novo\/wp-json\/wp\/v2\/media?parent=89"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}