W = work done by the spring on the toy car = 196 Joules
m = mass of the toy car = 2 kg
v₀ = initial velocity of the car when at rest = 0 m/s
v = final velocity of the car after spring does work on it = ?
According to work-change in kinetic energy, net work done on an object is same as the change in kinetic energy of the object . hence
Net work done = Final kinetic energy - initial kinetic energy
W = (0.5) m (v² - v₀²)
inserting the values
196 = (0.5) (2) (v² - (0)²)
v² = 196
v = sqrt(196)
v = 14 m/s