Question 919968
For the penknife,
{{{h(t)=-5t^2-10t+40}}}
{{{v(t)=-10-10t}}}
Find the time t, when {{{h(t)=0}}}
{{{-5t^2-10t+40=0}}}
{{{t^2+2t-8=0}}}
{{{(t+4)(t-2)=0}}}
One solution
{{{t-2=0}}}
{{{t=2}}}
a){{{v=-10-10(2)=-10-20=-30}}}{{{m/s}}}(Negative is downwards)
b){{{t=2}}}{{{s}}}
c)The parachutist falls at a constant velocity.
{{{10t[p]=40}}}
{{{t[p]=4}}} {{{s}}}
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{{{D=t[p]-t=4-2=2}}}{{{s}}}