[JimLFisher]

The force on the 100 kg mass is 100 times as great. However, as the mass is 100 times more, the acceleration is the same. As velocity is produced as a product of acceleration and time, as long as they are both falling from the same height, they are thus falling for the same amount of time and thus both strike the earth at the same velocity. This, of course ignores the retarding effect of air resistance.