Question 892682
{{{s=-(1/2)gt^2+v0*t+s0}}}
{{{s=-(1/2)(9.8)t^2+2t+7}}}
{{{s=-4.9t^2+2t+7}}}
Find t when,
{{{s=0}}}
.
.
.
{{{-4.9t^2+2t+7=0}}}
Use the quadratic formula,
{{{t=(-2 +- sqrt(2^2-4(-4.9)(7)))/(2(-4.9))}}}
{{{t=(-2+-sqrt(141.2))/(-9.8)}}}
Only the positive time makes sense here.
{{{t=(-2-11.883)/(-9.8)}}}
{{{t=1.41}}}{{{sec}}}