The $x-t$ graph of a particle moving along a straight line is shown in figure The $v-t$ graph of the particle is correctly shown by

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

A particle of mass $m$ is projected with velocity $v$ making an angle of ${45^o}$with the horizontal. The magnitude of the angular momentum of the particle about the point of projection when the particle is at its maximum height is (where $g = $ acceleration due to gravity)

Two seconds after projection a projectile is travelling in a direction inclined at $30^o$ to  horizontal, after one more second it is travelling horizontally. What is the magnitude and  direction of its velocity at initial point

A ball of mass $1 \;kg$ is thrown vertically upwards and returns to the ground after $3\; seconds$. Another ball, thrown at $60^{\circ}$ with vertical also stays in air for the same time before it touches the ground. The ratio of the two heights are

A piece of marble is projected from earth's surface with velocity of $19.6 \sqrt{2}\,m / s$ at $45^{\circ}.$ $2\,s$ later its velocity makes an angle $\alpha$ with horizontal, where $\alpha$ is $..........$