A2100 kg car starts from rest and accelerates at a rate of 2.6 m/s2 for 4.0 s. assume that the force acting to accelerate the car is acting in the same direction as its motion. how much work has the car done?

When the system is experiencing a uniformly accelerated motion, there are a set of equations to work from. In this case, work is energy which consist solely of kinetic energy. That is, 1/2*m*v2. First, let's find the final velocity.

a = (vf - v0)/t
2.6 = (vf - 0)/4
vf = 10.4 m/s

Then W = 1/2*(2100 kg)*(10.4 m/s)2
W = 113568 J = 113.57 kJ