the problem reads 

 

a sudden stop, a car's seatbelt provides the force that stops the passenger.

 

For a 80kg passenger,

what's the seatbelt force if a car goes from highway speed of 90.0km/h to rest in 5.1s ?

what is this called and where can i find videos to help me out

I'll give you some hints...

 

First, you need to find the acceleration of the passenger as the car stops.  To do this, first convert the initial speed of the car from km/hr to meters/second (http://www.aplusphysics.com/courses/regents/videos/Metric_System/Metric_System.html).

 

Next, calculate the acceleration of the passenger: http://www.aplusphysics.com/courses/honors/videos/KinEqns_Hon/KinEqns_Hon.html

 

Finally, once you know the passenger's acceleration, you can calculate the force using Newton's 2nd Law: http://www.aplusphysics.com/courses/honors/videos/N2Law_Regents/N2Law.html

Thanks Fizz you are the man.  Im gonna hang this up until tomorrow