A 35 kg child ziplines from rest on a platform 12 m high to the ground with negligible friction. In the last 8 m of the zipline, which is approximately horizontal, a braking mechanism applies a constant force opposing the motion to slow the child down so that she\textquotesingle s traveling at 2.5 m/s when she finally lands on the safety padding at the end. The padding compresses for1.5 s when the child lands on it and stops.  $\textasciitilde$  What is the magnitude of the force applied by the braking mechanism? 
选项为:A:$$350N$$  B:$$511N$$  C:$$525N$$  D:$$4090N$$  请回答其中一个选项.