Huh? I was already leaning forward. So just accelerate backwards
mah..... let Newton's 2nd Law (F = ma) handle the rest...
Also, once two secondary school kids on a bus were playing the
fool. One kid tossed a water bottle across the aisle at his friend.
The bottle missed, hit the window..... and fell onto my lap.

I beckoned the kid who tossed the bottle to come over. I stared
him down and growled at him in a low, threatening voice.
Then I whipped out my camera phone and pretended to take his
picture. I told him 'Your discipline master would be really
interested to know about this....'
I think he was scared sh*tless for the next few days. 
Newton 2nd law is more like:
Force = Rate of change of momentum leh.
Ahhh! Whatever! I need to head to school! ciao!