A car goes forward along a level road at constant velocity. The additional force needed to bring equilibrium is ...

no additional force is needed to bring the car to equilibrium.

the car is going forward on a level road at constant velocity. that means the velocity of the car remain same all the time.

we know that acceleration is the time rate of change of velocity. since the velocity of car does not change, the acceleration of the car must be zero.

according to newton's second law, net force is given as

F = ma

where F = net force, m = mass, a = acceleration

since a = 0,

F = m (0)

F = 0 N

since the net force is zero on the car, the car is already in equilibrium and hence no additional force is needed to bring equilibrium