I have a problem with the game engine. When I make a car move forward and it hits a ramp it does not land again if I hold down forward it just keeps flying crazily. Also are there any current ttorials for making in game characters that walk? Thanks in advance for any help. 
Can any1 answer???
Moderators need to lock threads and put on probation users that do this “You didn’t respond in 2 minutes so I’m going to post again because THAT will get people to respond” crap. You posted, just FREAKING WAIT for a response, this isn’t a chatroom, it’s a forum, sometimes responses take awhile.
As to your problem, you’re going to either have to post a blend file or give us quite a bit more details, there really isn’t enough information.
study physics
you cant use linear Velocity use DLoc or Force