A 1500 kg car is travelling due North at a speed of 25 m/s. Driver presses on the break and the car experiences a constant net force of 2 kN toward the South.  How long will it take the car to stop under the influence of this force?

First, we need to convert the force from kilonewtons (kN) to newtons (N) because the standard unit of force in physics is the newton.

1 kN = 1000 N

So, 2 kN = 2 * 1000 = 2000 N

Next, we use Newton's second law of motion, which states that the force acting on an object is equal to its mass times its acceleration (F = ma). We can rearrange this equation to solve for acceleration (a = F/m).

a = F/m = 2000 N / 1500 kg = 1.33 m/s²

However, the force is acting in the opposite direction to the car's motion, so the acceleration is negative.

a = -1.33 m/s²

Then, we use the equation of motion that relates final speed, initial speed, acceleration, and time (v = u + at), where v is the final speed, u is the initial speed, a is the acceleration, and t is the time. We rearrange this equation to solve for time (t = (v - u) / a).

The car is going to stop, so its final speed is 0 m/s.

t = (0 m/s - 25 m/s) / -1.33 m/s² = 18.8 seconds

So, it will take approximately 18.8 seconds for the car to stop under the influence of this force.