Derivative of position question

[jasonchiang97]

Homework Statement

Q:
The position of a dragonfly that is flying parallel to the ground is given as a function of time by r⃗ =[2.90m+(0.0900m/s2)t^2]i^− (0.0150m/s3)t^3j^ .

At what value of t does the velocity vector of the insect make an angle of 30.0 ∘ clockwise from the x-axis?
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Homework Equations

none

The Attempt at a Solution

What I did so far: Well I'm pretty sure the first step is to take the derivative of the position vector. I did that and got (0.18t)i^2-(0.045t^2)j^2.

I tried to use tan30=0.18t/0.048t^2 and solve for t

I get t=69.28 but I'm not sure if that is 100% correct

 

[RJLiberator]

Check this part of the question:

At what value of t does the velocity vector of the insect make an angle of 30.0 ∘ clockwise from the x-axis?

What can you defer from this?

Also,
I believe your evaluation of "t" has some mistakes.

 

[jasonchiang97]

never mind I got it

was trying to do it too fast and ended up making a careless mistake

thanks