G forces

Calculate car deceleration (as a multiple of gravitational acceleration g = 9.81 m/s²) when a vehicle in a frontal collision slows down uniformly from a speed 111 km/h to 0 km/h in a 1.2 meters trajectory.

Correct answer:

G =  40.4 g

Step-by-step explanation:

$$\begin{gathered} s=\frac{1}{2}a{t}^2=1.2m \\ 2s=a{t}^2 \\ a=\frac{\Delta v}{\Delta t} \\ v=at=\frac{2s}{t}=111km/h=30.833m/s \\ t=\frac{2s}{v}=\frac{2\cdot 1.2}{30.833}=0.0778378s \\ a=v/t=30.833/0.0778378=396.123m/s^2 \\ G=a/g=40.4\text{g} \end{gathered}$$

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