Réponses

2013-02-09T14:47:00+01:00

Bonjour,

 

On a la formule :

E_c = \frac{1}{2}mv^2\\

45 km/h = 12,5m/s

3906 = \frac{1}{2}m\times 156{,}25\\ 7812 = 156{,}25m\\ m = \frac{7812}{156{,}25} = 49{,}9968\text{ kg}