If the initial velocity of a projectile be doubled, keeping the angle of projection same, the maximum height reached by it will

A bullet is fired from a gun at the speed of $280\,ms ^{-1}$ in the direction $30^{\circ}$ above the horizontal. The maximum height attained by the bullet is $........\,m$ $\left(g=9.8\,ms ^{-2}, \sin 30^{\circ}=0.5\right):-$

The equation of motion of a projectile is:   $y = 12x - \frac{5}{9}{x^2}$. The horizontal component of velocity is $3\ ms^{- 1}$ . Given that $g = 10\ ms^{- 2}$ , .......... $m$ is the range of the projectile .

A cricket ball is thrown by a player at a speed of $20\,m / s$ in a direction $30^{\circ}$ above the horizontal. The maximum height attained by the ball during its motion is $........\,m$ $\left( g =10\,m / s ^2\right)$

Two stones having different masses $m_1$ and $m_2$ are projected at an angle $\alpha$ and $\left(90^{\circ}-\alpha\right)$ with same speed from same point. The ratio of their maximum heights is

A body is projected at $t = 0$ with a velocity $10\,ms^{-1}$ at an angle of $60^o$ with the horizontal. The radius of curvature of its trajectory at $t=1\,s$ is $R.$ Neglecting air resistance and taking acceleration due to gravity $g = 10\,ms^{-2},$ the radius of $R$ is   ........ $m$