Solve 2-D Motion: Find Direction at t=0 & t=3.5

[Amria]

A particle's trajectory is defined as x = (1/2t^3 - 2t^2) m and y = (1/2t^2 - 2t)m where t is in s.

What is the particle's direction of motion, measured from the x axis, at t=0 and t= 3.5, measured in degrees counterclockwise from the x axis.

I started out by plugging in t = 0 and t = 3.5 to the equations given. I then attemped to take arctan(y/x) in both cases to find the direction of motion. my answers for these, 0 degrees and 15.9 degrees respectively, both came back as wrong.

Any clues as to what I am doing wrong/how to do it right?

 

[Integral]

If you used the given equations, then you have found the LOCATION of the particle. What can you do to get information about the velocity of the particle?

 

[billiards]

Try differentiaing wrt t (for both x and y separately) to find the general equations for velocity.