Two particles in same vertical plane are thrown to strike at same time. One from ground and other from height $h$ vertically above it. Ground particle is thrown obliquly and it achives a maximum height $H$. The second particle is thrown horizontally with same speed. What can be maximum $h$ so that two particles strike in air.

For a projectile, the ratio of maximum height reached to the square of flight time is ($g = 10 ms^{-2}$)

A body is thrown with a velocity of $9.8 \,m/s$ making an angle of $30^o$ with the horizontal. It will hit the ground after a time ....... $\sec$

A projectile fired at $30^{\circ}$ to the ground is observed to be at same height at time $3 s$ and $5 s$ after projection, during its flight. The speed of projection of the projectile is $.........\,ms ^{-1}$(Given $g=10\,m s ^{-2}$ )

A projectile is thrown with velocity $U=20\ m/s ± 5\%$ at an angle $60^o.$ If the projectile falls back on the ground at the same level then    ......... $m$ of following can not be a possible answer for range.

A very broad elevator is going up vertically with a constant acceleration of $2\,m / s ^2$. At the instant when its velocity is $4\,m / s$ a ball is projected from the floor of the lift with a speed of $4\,m / s$ relative to the floor at an elevation of $30^{\circ}$. The time taken by the ball to return the floor is $..............\,s$ $\left(g=10\,m / s ^2\right)$