On foggy day two drivers spot in front of each other when 80 m apart, they were travelling 70 kmph and 80 kmph. Both apply brakes simultaneously which retards the car at the rate of 5 m/${\mathrm{s}}^2$. Which of the following statement is correct?

For the first car we get, 

72kmph = 72 ×$\frac{5}{18}$ = 20m/sec.

v² = u² + 2as₁

0 = (20)² + 2(-5)s₁

s₁ = 40m

For  the second car we get, 

 60kmph = 60 × $\frac{5}{18}$=16.62m/sec.

v² = u²+2as₂

0 = (16.62)²+2(-5)s₂

s₂ = 27.7m

The distance travelled by the two car = s₁ + s₂  = (40+27.7) = 67.7meter.

Since they are 80m apart from each other no collision will takes place.

Hence 67.7 $< 80$ , so the collision will be averted.