0

PR Om Aad

Satu kilogram udara dipanaskan secara reversibel pada tekanan konstan pada keadaan awal 300K dan 1 bar sampai volumenya menjadi tiga kali dari semula. Hitunglah W, Q, ∆U, dan ∆H untuk proses itu! Asumsikan untuk udara PV/T = 83,14 bar.cm3mol-1K-1 dan Cp = 29 mol-1K-1.
 
            Penyelesaian
*  Diketahui   :  m  = 1 kg  = 1000 g
                          P   =  konstant
                          T1  = 300 K
                          P1   = 1 bar
                           V2   = 3 V1  
                          PV/T = 83,14 bar.cm3mol-1K-1
                           Cp = 29 mol-1K-1
                          BM udara 28,97 g/gmol
*  Ditanya  :  W, Q, ∆U, dan ∆H
*  Jawab      : 
                        Pada keadaan 1
                                    PV/T = 83,14 bar.cm3mol-1K-1
                                    1(bar)* V1 / 300 (K)   = 83,14 bar.cm3mol-1K-1
                                                >> V1   = 24.942 cm3/mol
 
                                    Jadi   V2   = 3 V1  
                                                     =  3* 24.942
                                                     =  74.826 cm3mol-1
 
                        Pada keadaan 2
                                    PV/T = 83,14 bar.cm3mol-1K-1
                                    1(bar)* 74.826 (cm3mol-1) / (T2) (K)   = 83,14 (bar.cm3mol-1K-1)
                                                >> T2 =  900 (K)
 
                        Jumlah mol udara
                                    n  = m/BM
                                        = 1000/28,97
                                        =  34,52 mol
 
a.  W = – dV  = – dV =  – ( V2-V1)   =  – ( 74.826 – 24.942) =  49.884 barcm3mol-1
      maka untuk 1000 g udara >> Wt =  n . W
                                                           =  34,52 (mol) * 49.884 barcm3mol-1
                                                           =  1.721.995,68 barcm3
                                                =  1.721.995,68 (bar)* (105Nm-2)/ 1 bar* 1 cm3(10-6m3)
                                                = 17.219.956,8 Nm
                                                =  17.219.956,8 J 
 
b.  ∆H = dT  =  dT  = 29 ( T2 – T1) = 29 ( 900-300)  = 17.400 mol-1
     maka  untuk 1000 g udara ∆Ht = n. ∆H
                                                       = 34,52 * 17.400
                                                       = 600.648 J
 
c.   Q  = n. ∆Ht
            = 34,52 * 600.648
            =  20,73.106 J
 
d.  ∆U  = Q + W
            =  20,73.106 + 17.219.956,8 J 
            = 37,95.106J
0

Transducer

A transducer is a device that converts one type of energy to another. Energy types include (but are not limited to) electrical, mechanical, electromagnetic (including light), chemical, acoustic or thermal energy. While the term transducer commonly implies the use of a sensor/detector, any device which converts energy can be considered a transducer.

0

NASA

The webpages of The National Aeronautics and Space Administration

 

<embed src=”http://images.nationalgeographic.com/wpf/sites/video/swf/ngplayer_syndicated.swf&#8221; flashVars=”slug=us-space-shuttle-final-days-vin&img=http://video.nationalgeographic.com/exposure/core_media/ngphoto/image/37128_0_610x343.jpg&vtitle=Space%20Shuttle’s%20Final%20Days&caption=%3Cp%3EJune%2030,%202011%E2%80%94NASA’s%20space%20shuttle%20has%20been%20an%20icon%20of%20the%20U.S.%20space%20%20program%20for%20the%20past%2030%20years.%20Journey%20on%20one%20of%20the%20last%20shuttle%20%20missions%20to%20witness%20some%20final%20%22firsts%22%20made%20aboard%20this%20unique%20%20spacecraft.%3C/p%3E&permalink=http://video.nationalgeographic.com/video/player/news/space-technology-news/us-space-shuttle-final-days-vin.html&share=true” name=”flashObj” width=”460″ height=”321″ seamlesstabbing=”false” allowfullscreen=”true” type=”application/x-shockwave-flash” pluginspage=”http://www.macromedia.com/shockwave/download/index.cgi?P1_Prod_Version=ShockwaveFlash”></embed&gt;