30000÷(15×60)=33,3 (40000+30000)÷(60+33,3)=750м/мин 750х60=45км/ч
v=1/2*pi*корень кв(m<span>/k) </span>m=0<span>,1</span>
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<span>1) E=-d(фи)/dr
</span><span>6) A=q*(фи1-фи2)</span>
E=3/2*k*T
E=1.5*1.38*10^-23*350=724.5*10^-23