It takes 242 kJ of work to accelerate a car from 20.2 m/s to 28.2 m/s. What is the car's mass?

change in KE = 1/2 mv2^2 - 1/2mv1^2 = 1/2m(v2^2-v1^2)

where v2 and v1 are the final and initial speeds
242 = KE
plug in numbers to get ans(mass) :D