<span>дано:</span>
<span>T</span><span>1=10’</span><span>C</span><span>=285</span><span>K</span>
<span>m</span><span>2=0,6</span><span>kr</span>
<span>T</span><span>2=100’</span><span>C</span><span>=373</span><span>K</span>
<span>c</span><span>=4200Дж/кг К</span>
<span>q=12MДж=12000000Дж</span>
<span>Q</span><span>1=0,25Q2</span>
<span>m</span><span>1</span><span>-?</span>
<span> </span>
<span>Q</span>1=<span>c</span>1<span>m</span>1(<span>T</span>-<span>T</span>1)-<span>нагрев </span><span> </span>воды <span>c</span>1=4200Дж/кг К
<span>Q</span>2=qm2 <span>–горение дров</span>
Q<span>1=0,25</span>Q<span>2</span>
<span>Q</span><span>2=12000000*0,6=7200000Дж</span>
<span>m</span><span>1=</span><span>Q</span><span>1/</span><span>c</span><span>(</span><span>T</span><span>2-</span><span>T</span><span>1)</span>
<span>m</span><span>1=0,25*7200000/4200*90=4</span><span>,</span><span>7</span><span>6</span><span>кг</span>
<span> </span>