Given,

u=36 km/h is the initial velocity.

v = 0 is the final velocity.

The three-mass wheeler’s is m1=400 kg.

The driver’s mass is m2 = 65 kg.

The time it took to bring the car to a complete stop was 4.0 seconds.

Acceleration, a = v- u/t = (0 – 10)/ 4 = – 2.5 m/s

Now, F = (m1 + m2)/ a = (400 + 65) x (-2.5)

= – 1162.5 N = – 1.16 x 103 N

The negative symbol indicates that the force is slowing down.