A truck is moving with a constant velocity of $54km{h}^{-1}$. In which direction (angle with the direction of motion of truck) should a stone be projected up with a velocity of $20m{s}^{-1}$, from the floor of the truck, so as to appear at right angles to the truck, for a person standing on earth?

Q. A truck is moving with a constant velocity of $54\text{km/h}$. In which direction (angle with the direction of motion of truck) should a stone be projected up with a velocity of $20\text{m/s}$ relative to truck, so that for a person standing on the earth stone appears to be at right angles to the truck ?

Q. A truck is moving with a constant velocity of $54km{h}^{-1}$. In what direction should a stone be projected up with a velocity of $20m{s}^{-1}$, from the floor of the truck, so as to appear at right angles to the truck, for a person standing on earth?

Q. A truck is moving with a constant velocity of 54 $km{h}^{-1}$ In which direction (angle with the direction of motion of truck) should a stone be projected up with a velocity of 20 $m{s}^{-1}$, from the floor of truck, so as to appear at right angles to the truck, for a person standing on earth?

Q. A truck is moving with a constant velocity of $54\text{km/h}$. In which direction (angle with the direction of motion of truck) should a stone be projected up with a velocity of $20\text{m/s}$ relative to truck, so that for a person standing on the earth stone appears to be at right angles to the truck ?

Q. A truck starts from origin, accelerating with $am{s}^{-2}$ in positive x-axis direction. After $2s$, a man standing at the starting point of the truck projected a ball at an angle ${30}^o$ with velocity-$vm{s}^{-1}$. Find the relation between $a$ and $v$ such that the ball hits the truck. (Assume that truck is moving on horizontal plane and the man projected the ball from the same horizontal level of truck).