A body is projected horizontally from a height of $78.4m$ with a velocity $10{ms}^{-1}$. Its velocity after $3$ seconds is ____ ($g=10{ms}^{-1}$). (Take direction of projection on $\hat{i}$ and vertically upward direction on $\hat{j}$):

Q. A body is projected vertically upwards with a velocity of $10{ms}^{-1}$ and another body is projected simultaneously from the same point with a velocity of $20{ms}^{-1}$ at an angle of $\frac{\pi }{6}$ with the horizontal. The distance between the two bodies after one second from the time of projection is (Acceleration due to gravity is $10{ms}^{-2}$)

Q. A body projected vertically upward with a velocity $v$ at $t=0$ is found at a height $h$ after $1$ second and after further $6$ seconds, it is found at the same height ($g=10m{s}^{-2}$). Then,

Q. At a height of $15m$ from ground velocity of a projectile $\overrightarrow{v}=(10\hat{i}+10\hat{j})$ and ($g=10m{s}^{-2}$ )

Q. A body is projected vertically upwards with a velocity $u$. It crosses a point in its journey at a height $h$ meter twice, just after $1$ and $7$ seconds .The value of $u$ in $m{s}^{-1}$ is $(g=10m{s}^{-2})$