<p>A rocket is launched with an intial velocity of zero, and with acceleration in feet per second per second defined by </p>
<p>a (t)= 20e^(-t/2) for 0 to 10
= -16 for t>10</p>
<p>A) at what time does the rocket begin to descend?</p>
<p>PS. THis is from Amsco's AB/BC Calculus review book. If you have it, please just look up the answer and respond ASAP! Thanks. You're chill. =)
PLEASE. we're desperate.</p>
<p>v(t)=-40e^(-t/2) for 0 to 10
and
v(t)=-16t for t>10
yeah, so that doesn't make any sense...does it? maybe you copied something wrong? because the only time the velocity is zero in either of those equations (it's never zero in the first one) is when t=0. Maybe i made some error or...not</p>
<p>The rocket begins to descend when its velocity is negative.</p>
<p>Infinitesimally negative number = 0.</p>
<p>v(t) = integral(20e^(-t/2))</p>
<p>v(t) = 0, solve for t</p>
<p>your logic is flawed^</p>
<p>For one, as i stated, the integral of 20e^(-t/2) is -40e^(-t/2), which is ALWAYS negative. Secondly, it approaches zero as t goes to infinity.</p>
<p>I am definitely thinking the OP copied the problem wrong or something is missing.</p>
<p>Sorry, I wasn't paying attention, lol.</p>
<p>I don't really care about other people's homework.</p>