Newton's second law of motion is mathematically expressed as #F = m a#; where #F# is the force exerted on an object, #m# is the mass of the object, and #a# is the acceleration of that object.

In this case, the mass of the car and the force exerted on it are provided as information.

Let's plug in the values into the formula #F = m a#:

#Rightarrow 600# #"N" = 1200# #"kg" times a#

Let's express #"N"# using SI base units:

#Rightarrow 600# #"kg m s"^(- 2) = 1200# #"kg" times a#

#Rightarrow frac(600 " kg m s"^(- 2))(1200 " kg") = frac(1200 " kg")(1200 " kg") times a#

#Rightarrow frac(1)(2)# #"m s"^(- 2) = 1 times a#

#therefore a = 0.5# #"m s"^(- 2)#

Therefore, the acceleration of the car is #0.5# #"m s"^(- 2)# when its engine exerts a force of #600# #"N"#.