$A$ mass $m$ is tied to one end of a spring and whirled in a horizontal circle with constant angular velocity. The elongation in the spring is $1 \ cm$. If the angular speed is doubled,the elongation in the spring is $6 \ cm$. The original length of the spring is (in $cm$)

$A$ vehicle is moving with uniform speed along $3$ different shaped roads: horizontal,concave,and convex. The surface of the road on which the normal reaction on the vehicle is maximum is

The masses of blocks $A$ and $B$ are $100 \, kg$ and $200 \, kg$ respectively. The coefficient of friction between $A$ and $B$ is $0.2$,and the coefficient of friction between $B$ and the ground is $0.3$. What force $F$ (in $N$) must be applied to block $B$ to make it move?

An object of mass $M$ is placed on a rough horizontal surface (coefficient of friction $\mu$). $A$ person tries to pull the object by applying a horizontal force,but the object does not move. The force $F$ exerted by the surface on the object is:

$A$ ball connected with a string is released at an angle of $45^{\circ}$ with the vertical,as shown in the figure. If the mass of the box is equal to the mass of the ball,the acceleration of the box at this instant will be:

$A$ bead of mass $m$ can slide on a frictionless fixed ring of radius $r$. With the help of two identical springs of force constant $k$,it is connected to two diametrically opposite nails $A$ and $B$,each of which is at a distance $0.5r$ from the centre $O$ of the ring. The relaxed length of each spring is negligible compared to the radius of the ring. The bead is given a small velocity. What can you predict for the further motion of the bead before any of the springs strikes a nail?