A car

A car weighing 1.05 tonnes driving at the maximum allowed speed in the village (50 km/h) hit a solid concrete bulkhead. Calculate height it would have to fall on the concrete surface to make the impact intensity the same as in the first case!

Correct result:

h =  9.6451 m

Solution:

$$\begin{gathered} m=1.05\text{ t}\to \text{ kg}=1.05\cdot 1000\text{ kg}=1050\text{ kg } \\ v=50\text{ km/h}\to \text{ m/s}=50\mathrm{/}3.6\text{ m/s}=13.88889\text{ m/s } \\ g=10{\text{m/s}}^2 \\ v=gt \\ t=v\mathrm{/}g=13.8889\mathrm{/}10={\displaystyle \frac{25}{18}}\doteq 1.3889\text{ s } \\ h={\displaystyle \frac{1}{2}}\cdot g\cdot t^2={\displaystyle \frac{1}{2}}\cdot 10\cdot 1.3889^2={\displaystyle \frac{3125}{324}}=9.6451\text{ m} \end{gathered}$$

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