Let F = force to stop the car.

Then, F = ma

F = 940*a ----------------(1)

What is "a"?

It is deceleration, of course.

Given:

Initial velocity, Vo = 38km/hr = (38km/1hr)(1000m/1km)(1hr/3600sec) = 10.555.... m/sec

Final velocity, Vt = 0

Distance travelled, s = 1.8 cm = (1.8cm)(1m/100cm) = 0.018 m

Distance = (average velocity) * time

s = (1/2)(Vo +Vt)*t

0.018 = (1/2)(10.555... +0)*t

t = 0.018 / (10.555... /2) = 0.00341 sec.

Velocity at t = (initial velocity) + a*t

Vt = Vo +at

0 = 10.555... +a(0.00341)

a = -10.555... /0.00341 = -3095.47 m/sec/sec

Hence,

F = ma

F = 940(-3095.47) = -2,909,742 newtons <---almost 3 million newtons!

Negative, because F is against the direction of the car.