Derive equation of motion of body moving in two dimensions
$\overrightarrow v \, = \,\overrightarrow {{v_0}} \, + \overrightarrow a t$ and $\overrightarrow r \, = \,\overrightarrow {{r_0}} \, + \overrightarrow {{v_0}} t\, + \,\frac{1}{2}g{t^2}$.
If the position vector of a particle is
$\vec r = - \cos \,t\hat i + \sin \,t\hat j - 18\,t\hat k$
then what is the magnitude of its acceleration ?
The position vector of an object at any time $t$ is given by $3 t^2 \hat{i}+6 t \hat{j}+\hat{k}$. Its velocity along $y$-axis has the magnitude