Hello>
Can someone help me with this?

A vehicle travelling skidding 81ft to point of impact. How do you determine how fast the vehicle was going?

Well, I don't see any ways of solving this. Did you miss any information, such as the force of impact, the frictional force..

A vehicle travelling skidding 81ft to point of impact. How do you determine how fast the vehicle was going?


You need the coefficient of friction between the tires and the road if you wish to calculate it. There are lots of sites that have approximations if you wish to look at them (they estimate 37-44 mph on dry blacktop)

speed estimates, skid marks, speedchart (http://www.e-z.net/~ts/speedch.htm)
Skid Marks (http://www.claimrep.com/Skidmarks.htm)
Accident reconstruction speed calculator (http://www.harlan-mcgee.com/speed-calc.htm)

Google more sites. (http://lmgtfy.com/?q=skid+marks+speed)