Respostas

2014-08-07T13:57:01-03:00
vm= \frac{x}{t}

vm*t=x

\boxed{t= \frac{x}{vm}}

Primeiro lado,

t= \frac{5:5}{100:5}= \frac{1}{20}h

Segundo lado,

t_2= \frac{5:5}{120:5}=  \frac{1}{24}h

Terceiro lado,

t_3= \frac{5:5}{120:5}= \frac{1}{24}h

Quarto lado,

t_4= \frac{5:5}{150:5}= \frac{1}{30}h


A velocidade média do percurso todo é dada por:

vm= \frac{d_1+d_2+d_3+_d_4}{t+t_2+t_3+t_4}

vm= \frac{5+5+5+5}{ \frac{1}{20}+ \frac{1}{24}+ \frac{1}{24}+ \frac{1}{30}}

MMC(20,24,30)=120

 \frac{1}{20} + \frac{1}{24}+ \frac{1}{24}+ \frac{1}{30}= \frac{6+5+5+4}{120}= \frac{20}{120}= \frac{2}{12}= \frac{1}{6}h

vm= \frac{20}{ \frac{1}{6}}= \frac{20}{1}* \frac{6}{1}=\boxed{120km/h}


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