$A$ car is moving at a speed of $72 \, km/hr.$ The diameter of its wheels is $0.5 \, m.$ If the wheels are stopped in $20$ rotations by applying brakes,then the angular retardation produced by the brakes is ............ $rad/s^2$. (in $.5$)

An aircraft executes a horizontal loop with a speed of $150\, m/s$ with its wings banked at an angle of $12^\circ$. The radius of the loop is .......... $km$ $(g = 10\, m/s^2 \text{ and } \tan 12^\circ = 0.2125)$

$A$ particle of mass $10\, g$ moves along a circle of radius $6.4\, cm$ with a constant tangential acceleration. What is the magnitude of this acceleration if the kinetic energy of the particle becomes equal to $8 \times 10^{-4}\, J$ by the end of the second revolution after the beginning of the motion? .............. $m/s^2$

Two projectiles are thrown with the same range $R$. If their maximum heights are $h_1$ and $h_2$ respectively,then what is the value of the range $R$?

$A$ stone of mass $0.25 \; kg$ is tied to the end of a string and is being whirled in a horizontal circle of radius $1.5 \; m$ with a speed of $40 \; rev./min$. If the speed of the stone is increased beyond the maximum permissible value and the string breaks suddenly,which of the following correctly describes the trajectory of the stone after the string breaks?
$(a)$ The stone moves radially outward.
$(b)$ The stone flies off tangentially from the instant the string breaks.
$(c)$ The stone flies off at an angle with the tangent whose magnitude depends on the speed of the particle.

The figure shows a sphere of mass $500 \ g$ moving in a steady flow of air in the $x$-direction. The air-stream exerts an essentially constant force of $0.9 \ N$ on the sphere in the $x$-direction. If at $t = 0$ the sphere is moving as shown in the figure,determine the time required for the sphere to cross the $y$-axis again in $\sec$. (in $.66$)