Ep=3/2KT=3/2*1.38*10^-23JK^-1*400K=8.28*e-21
平动动能总和:8.28*e-21*3*e25=248400J
p=2/3nEp=2/3N/vEp=2/3*3*e25/10*8.28*e-21=1658Pa