$\frac{$\Delta$T }{T}$=1+$\frac{h}{R}$=1+$\frac{2,5}{6400}$=1,0003$\Delta$T=1,0003T $\Rightarrow$$\Delta$T>T$\Rightarrow$chu ky tang thi dong ho chay cham lai
$\theta$=86400$\times $$\frac{h}{R}$=86400$\times $$\frac{2,5}{6400}$=33,75s
$\Rightarrow$dong ho chay cham 33,75s