作者Honor1984 (希望愿望成真)
看板TransPhys
标题Re: [考古] 请问三题考古计算题
时间Tue Jul 8 18:07:24 2008
※ 引述《flygey (努力达成目标)》之铭言：
: 1.(a)A Carnot engine operates between a hot reservoir at 320K and a cold one
: at 260K. If the engine absorbs 500J as heat cycle at the hot reservoir,
: how much work per cycle does it deliver?
: (b)If the engine working in reverse functions as a refrigerator between the
: same two reservoirs,how much work per cycle must be supplied to remove
: 1000J as heat from the cold reservoir?
: 2.An electric dipole with dipole moment →p=(3.00i+4.00j)(1.24x10^-30 C‧m)
: is in an electric field →E=(4000 N/C)i
: (a)What is the potential energy of the electric dipole?
: (b)What is the torque acting on it ?
: (c)If an external agent turns the dipole until its electric dipole moment is
: →p=(-4.00i+3.00j)(1.24x10^-30 C‧m), how much work is done by the agen?
: 3.在温度T很低的时候,许多固体的定容摩耳比热Cv与温度的关系可以近似为Cv=AT^3,
: 其中A与特定的材料有关,对铝而言,A=3.15x10^-5 J/molx k^4.
: 求；4.00 mol 的铝,温度由5.00K上升到10.0K时,entropy(熵)的改变量.
S = 积分 nCv dT / T
= 积分nAT^2 dT
= (1/3)nA[(Tf)^3 - (Ti)^3]
= (1/3)*4*3.15x10^(-5) * [10^3 - 5^3] (J/k)
: 请版友帮解感谢
: 感谢帮忙
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