If two vectors $\vec{A} = 4\hat{i} + n\hat{j} + 2\hat{k}$ and $\vec{B} = 2\hat{i} + 2\hat{j} - \hat{k}$ are mutually perpendicular to each other then value of 'n' is

A particle completes 2 revolutions in a circular path of radius 3 cm. The angular displacement of the particle will be (in radian)

A car is travelling at 40 m/s on a circular path of radius 40 m. It is increasing its speed at the rate of $2\ \text{m/s}^2$. Its net acceleration is (in $\text{m/s}^2$) nearly

Two spheres are projected at angles $30^\circ$ and $45^\circ$ with the horizontal. The maximum height reached by both is same. The ratio of their initial velocities is, $\left(\sin 45^\circ = \dfrac{1}{\sqrt{2}}, \sin 30^\circ = 0.5\right)$