Question

A 1200 kg car accelerates to the right at 7m/s2 along a special frictionless track. Determine the magnitude and direction of the force the engine exerts to accelerate the car?
A wind blows heavy winds into the car's path.As a result the car's acceleration slows to 4.5m/s2. If the engine is exerting the same force it was in part a, how much force does the wind exert on the car to slow acceleration.

Answer 1

Part 1:
Use F = m a to solve for the engine force F, in Newtons

Part 2:
In this case F, the net force, is F = F(engine) - F(wind)

Use F(engine) from Part 1 and the new lower value of acceleration (a) to solve for F(wind)

F(air) = F(engine) - m a

Answer 2

Just as an aside: A car (at least, a car as we understand it, with four wheels rotating on the ground) would not be able to accelerate on a frictionless track. The force providing the acceleration is the frictional force between the tires and the track. Some sort of "air car" (using, for example, a big fan) would, however, be able to accelerate on a frictionless track.