<span style="color:#333333;font-family:Helvetica, Arial, sans-serif;font-size:13px;line-height:16.8999996185303px;">The 60W fan of a central heating system is to circulate air through the ducts. The analysis of the flow shows that the fan needs to raise the pressure of air by 50 Pa to maintain the flow. The fan is located in the horizontal flow section whose diameter is 30 cm at both the inlet and outlet. Determine the highest possible average flow velocity in the duct.</span> <div><span style="color:#333333;font-family:Helvetica, Arial, sans-serif;font-size:13px;line-height:16.8999996185303px;"><br></span></div> <div><span style="color:#333333;font-family:Helvetica, Arial, sans-serif;font-size:13px;line-height:16.8999996185303px;"></span><div style="text-align:left;"><img src="http://thimg.todayhumor.co.kr/upfile/201503/1427197169Tr977EfJiiSdcBtK9buE.jpg" width="679" height="389" alt="b2.jpg" style="border:none;"></div><br></div> <div><span style="color:#333333;font-family:Helvetica, Arial, sans-serif;font-size:13px;line-height:16.8999996185303px;"><br></span></div> <div><font color="#333333" face="Helvetica, Arial, sans-serif"><span style="font-size:13px;line-height:16.8999996185303px;">문제만 보고 완전 멘붕왔다가 그림 구하고선 좀 나아졌는데, 해결하지 못하는건 여전하네요..</span></font></div> <div><font color="#333333" face="Helvetica, Arial, sans-serif"><span style="font-size:13px;line-height:16.8999996185303px;"><br></span></font></div> <div><font color="#333333" face="Helvetica, Arial, sans-serif"><span style="font-size:13px;line-height:16.8999996185303px;">질량도 없는데 이걸 어떻게 풀어야 하는건가요?</span></font></div> <div><font color="#333333" face="Helvetica, Arial, sans-serif"><span style="font-size:13px;line-height:16.8999996185303px;"><br></span></font></div> <div><font color="#333333" face="Helvetica, Arial, sans-serif"><span style="font-size:13px;line-height:16.8999996185303px;">대학교에 8년만에 복학하다보니 아무것도 기억이 안나네요 ``</span></font></div>