s = \frac{at^2}{2}
a = \frac{2s}{t^2}
a = \frac{2 * 200m}{(20 s)^2} = 1 m/s^2
-----
a = \frac{\Delta v}{\Delta t}
Dane:
a = 1 m/s^2
\Delta t = 20 s
\Delta v = ?
Samochód rusza z v=0, więc:
\Delta v = 20s * 1m/s^2 = 20 m/s
20m-----------1s
x[m]-----------3600s
-----------------------------z proporcji:
x = \frac{20m * 3600s}{1s} = 72000 m = 72 km
v auta = 72km/3600s = 72km/godz