(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

The following describes the position of a body as a function of time: [itex]X(t)=9\cdot cos(1.2t)\cdot e^{-t/10}[/itex].

What is the velocity of the body at t=17sec ?

2. The attempt at a solution

I'm trying to use the formula [itex]v(t)=\frac{dr}{dt}[/itex] in order to get the velocity and I get: [itex]-9\cdot e^{\frac{-17}{10}}\cdot [sin(1.2\cdot 17)\cdot 1.2+\frac{1}{10}\cdot cos(1.2\cdot 17)]=-1.975[/itex]

I guess negative velocity means the body is travelling in the oposite direction but is seems a little odd. Could this be the right answer?

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# Homework Help: Calculating velocity at a certain time

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