Question

it dangerous to jump out of moving bus why?

Answer 1

It's harmful as the bus is in motion and if we jump then we can get wounded....

Answer 2

Hey...!! HERE IS YOUR ANSWER....!!

According to NEWTON'S 1ST LAW OF MOTION 
Every object has inertia , and it will try to avoid the change in its interia. 

When you are in bus, you are moving with the velocity of bus with respect to ground. So you have the interia which can be understood as your momentum in this case. So when you jump out of a bus, you change your speed from a finite value to zero instantaneously, which causes an abrupt change in momentum, which your body will try to resist. So your upper body will still be in motion while your feet are still. It means you will definitely fall down. So it is advised not to jump from a moving bus and if indeed want to then try to run with it in same direction for some time gradually decreasing your speed.

HOPE IT'S WILL HELP YOU A LOT...!!
@ujjwalusri