# Magnitude and angle of particle direction-please help!

A 0.26 kg particle moves in an xy plane according to x(t) = - 10 + 2 t - 3 t3(t cubed) and y(t) = 29 + 3 t - 4 t2 (t squared), with x and y in meters and t in seconds. At t = 2.0 s, what are (a) the magnitude and (b) the angle (within (-180°, 180°] interval relative to the positive direction of the x axis) of the net force on the particle, and (c) what is the angle of the particle's direction of travel?

To solve this question I differentiated the two equations given and also found the accceleration.I then subbed in my value for t (t=2). After some more calculations I got 31.04 as my answer for part (a)146.309 degrees for part (b) and 123.69 degrees for part (c)
These answers are wrong and i cant understand where I am going wrong.
Any help with this problem would be much appreciated!

## Answers and Replies

ehild
Homework Helper
A 0.26 kg particle moves in an xy plane according to x(t) = - 10 + 2 t - 3 t3(t cubed) and y(t) = 29 + 3 t - 4 t2 (t squared), with x and y in meters and t in seconds. At t = 2.0 s, what are (a) the magnitude and (b) the angle (within (-180°, 180°] interval relative to the positive direction of the x axis) of the net force on the particle, and (c) what is the angle of the particle's direction of travel?

To solve this question I differentiated the two equations given and also found the accceleration.I then subbed in my value for t (t=2). After some more calculations I got 31.04 as my answer for part (a)146.309 degrees for part (b) and 123.69 degrees for part (c)
These answers are wrong and i cant understand where I am going wrong.
Any help with this problem would be much appreciated!

Yes, your answers are wrong. But we can not do anything if you do not show your work in detail.

ehild