Question

cuanto se demora un objeto en caer desde una altura de 80 metros

Answer 1

Magnitudes
$t=?$
$h=80m$
$g=9.8 m/s$
$v_{0} =0$

Formulas:
1. $(v_{f})^{2} =(v_{0})^{2} +2gh$
2. $v_{f} =v_{0} +2gt$

Resolviendo ecuaciones:
1. $(v_{f})^{2} =(v_{0})^{2} +2gh$
$\sqrt{(v_{f})^{2}} = \sqrt{(v_{0})^{2} +2gh}$
$v_{f}=\sqrt{(v_{0})^{2} +2gh}$
$v_{f}=\sqrt{( 0 m/s)^{2} +2(9.8 m/s^{2} )(80 m)$
$v_{f}=\sqrt{1568 m/s^{2}$
$v_{f}=39.59 m/s$

2. $v_{f} =v_{0} +2gt$
$t = \frac{v_{f} - v_{0}}{g}$
$t = \frac{39.59 m/s - 0}{9.8 m/s^{2} }$
$t = \frac{39.59 m/s}{9.8 m/s^{2} }$
$t=4.04 s$