A particle moving in the $x$ -y plane has a velocity $\mathbf{v}=7.25 \mathbf{i}+3.48 \mathbf{j} \mathrm{m} / \mathrm{s}$ at a certain instant.
If the particle then encounters a constant acceleration $\mathbf{a}=0.85 \mathbf{j} \mathrm{m} / \mathrm{s}^{2},$ determine the amount of time which must pass before the direction of the tangent to the trajectory of the particle has been altered by $30^{\circ}$