How Do Mass and Speed Affect Kinetic Energy in Cars?

[me_and_you]

Kinetic Energy and cars... Please help

Homework Statement

One car has twice the mass of a second car, but only half as much kinetic Energy. When both cars increase their speed by 6.0 m/s, they then ave the same kinetic energy. What were the original speeds of the two cars.

Homework Equations

Im not sure but i think its:

KE=.5mv_f²-.5mv_i²

The Attempt at a Solution

I manipulated the above equation by making KE multiplied by .5 and then removing the .5 from both masses.This however got me no where so could someone please help?

 

[jgens]

Try writing out the intial and final kinetic energy of each car and then go from there.