(Solved): The acceleration of a particle moving only on a horizontal xy plane is given by \\( \\vec{a}=3 t \\ ...

The acceleration of a particle moving only on a horizontal xy plane is given by \\( \\vec{a}=3 t \\hat{i}+4 t \\hat{j} \\), where \\( \\vec{a} \\) is in meters per secondsquared and \\( t \\) is in seconds. At \\( t=0 \\), the position vector \\( \\vec{r}=(23.0 \\mathrm{~m}) \\hat{i}+(45.0 \\mathrm{~m}) \\hat{j} \\) locates the paticle, which then has the velocity vector \\( \\vec{v}=(7.10 \\mathrm{~m} / \\mathrm{s}) \\hat{i}+(2.30 \\mathrm{~m} / \\mathrm{s}) \\hat{j} \\). At \\( t=4.40 \\mathrm{~s} \\), what are (a) its position vector in unit-vector notation and (b) the angle between its direction of travel and the positive direction of the \\( x \\) axis? (a) Number \\( \\hat{\\boldsymbol{i}}+ \\) \\( \\widehat{j} \\) Units (b) Number Units