  We derive the Friedmann-like equations in braneworld cosmology by imposing
the first law of thermodynamics and Bekenstein's area-entropy formula on the
apparent horizon of a Friedmann-Roberston-Walker universe in both
Randall-Sundrum II gravity and Dvali-Gabadadze-Porrati gravity models. Israel's
boundary condition plays an important role in our calculations in both cases,
besides the first law of thermodynamics and Bekenstein's area-entropy formula.
The results indicate that thermodynamics on the brane world knows the behaviors
of gravity.
