Question

Un corp cu masa de 500 g cade liber de la h=? si ajunge la sol cu v=9,8 m/s
Se neglijeaza forta de frecare cu aerul si se considera acceleratia gravitationala= 9,8 N/Kg
a) h=?
Repede,va rog frumos!

Answer 1

mV²/2 = mgh;   h = V²/2g
h = 9,8²/2·9,8 = 9,8/2 = 4,9m

Answer 2

$m_1=m_2=500 \ g=0,5 \ kg \\ v=9,8 \ m/s \\ g=9,8 \ N/kg \\ E_c=E_p \\ \boxed{h-?} \\ \bold{Rezolvare:} \\ \boxed{E_c=\frac{m \cdot v^2}{2}} \ \ \ \ \ \ \ \ \ \ \boxed{E_p=m \cdot g \cdot h} \\ E_c=E_p; \ \ \Rightarrow \frac{\not{m} \cdot v^2}{2}=\not{m} \cdot g \cdot h; \ \ \Rightarrow \frac{v^2}{2}=g \cdot h \\ g \cdot h=\frac{(9,8 \ m/s)^2}{2}=\frac{96,04 \ m^2/s^2}{2}=48,02 \ m^2/s^2$
$h=\frac{48,02 \ m^2/s^2}{g}=\frac{48,02 \ m^2/s^2}{9,8 \ N/kg}=\frac{48,02 \ m^{\not{2}}/\not{s^2}}{9,8 \ \not{m}/\not{s^2}} \\ \Rightarrow \boxed{h=4,9\ m \bold{\approx 5 \ m}}$